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Aspiration Windows

GerdIsenberg — Wed, 01 Nov 2017 08:40:20 GMT

Home * Search * Alpha-Beta * Aspiration Windows

		Aspiration windows are a way to reduce the search space in an alpha-beta search. The technique is to use a guess of the expected value (usually from the last iteration in iterative deepening), and use a window around this as the alpha-beta bounds. Because the window is narrower, more beta cutoffs are achieved, and the search takes a shorter time. The drawback is that if the true score is outside this window, then a costly re-search must be made. Typical window sizes are 1/2 to 1/4 of a pawn on either side of the guess.
The Non-Euclidean Window ^[1]

Gradual Widening

Some programs, such as Crafty, also use a gradual widening on re-searches. For instance, if the window is, in pawns:

$[g - 1/4, g + 1/4]$

and the search fails high, the next search would be

$[g - 1/4, g + 1]$

It's important to note that the bound that didn't fail is unchanged. In a basic alpha-beta without search instability, one could have done the next search on

$[g + 1/4, g + 1]$

instead. However, a fully fledged search is typically full of search instability, and it will often happen that the above re-search will fail low! This is why it is best to only widen the bound that fails, and leave the other bound unchanged.

Modern engines, like Robbolito or Stockfish, start with a rather small aspiration window, and increase the bound that fails in an exponential fashion.

PVS and Aspiration

Using aspiration windows together with the principal variation search (PVS) causes some additional complications.

PVS and Aspiration

Publications

Hermann Kaindl, Reza Shams, Helmut Horacek (1991). Minimax Search Algorithms with and without Aspiration Windows. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 13, No. 12
Reza Shams, Hermann Kaindl, Helmut Horacek (1991). Using Aspiration Windows for Minimax Algorithms. IJCAI 1991, pdf

Forum Posts

1995 ...

Question about aspiration window by Werner Inmann, CCC, August 14, 1998
aspiration windows by James Long, CCC, November 27, 1998
Aspiration Rules... by Chris Pile, rgcc, February 5, 1999
Aspiration search by James Robertson, CCC, April 20, 1999
Aspiration search by Scott Gasch, CCC, August 13, 1999

2000 ...

Aspiration window by Bas Hamstra, CCC, January 20, 2002
Exact value of second best move in AlphaBeta with aspiration Window by Martin Bauer, CCC, August 01, 2002
Aspiration search, PVS by Russell Reagan, CCC, December 28, 2002
Unstable aspiration search by Sune Fischer, CCC, February 10, 2003
Question about aspiration search by Jaime Benito de Valle Ruiz, CCC, March 23, 2004
What is a common Aspiration window? by Joachim Rang, CCC, March 26, 2004
aspiration search question by Daniel Shawul, CCC, May 13, 2004
Q. Aspiration, PVS, Fail-Soft by David B. Weller, CCC, July 02, 2004
PVS and aspiration windows by Tord Romstad, CCC, August 06, 2004

2005 ...

Aspiration Window sizes by Renze Steenhuisen, CCC, March 14, 2005
Bounds for aspiration window re-search by Sven Schüle, CCC, March 17, 2009
A way to improve PVS by Sergei S. Markoff, CCC, September 07, 2009

2010 ...

Apiration window by Don Dailey, CCC, March 27, 2010
A few general questions... by Bill Henry, CCC, January 29, 2012 » Root, Exact Score
optimal aspiration window for stockfish question by Uri Blass, CCC, March 12, 2012 » Stockfish
Aspiration Windows: Rubbish! by Matthew R. Brades, CCC, July 16, 2012
Aspiration window - effect? Issue with hashtables?! by Jens Bæk Nielsen, CCC, December 28, 2012
Aspiration Windows by Jerry Donald, CCC, January 11, 2013
Aspiration windows by Marco Pampaloni, CCC, May 14, 2013
Your experience with PVS + Aspiration window by Fabio Gobbato, CCC, October 07, 2014 » Principal Variation Search, PVS and aspiration
Solving a fail low situation at the root by Alberto Sanjuan, CCC, November 03, 2014 » Fail-Low

2015 ...

Parallel aspiration windows by Giuseppe Cannella, CCC, July 29, 2015
Restarting iterative deepening by Harm Geert Muller, CCC, December 09, 2015 » Fail-Low, Iterative Deepening

2016

Dynamic aspiration window by Sergei S. Markoff, CCC, May 26, 2016
Aspiration Windows on the root search -- Determining margin by Andrew Grant, CCC, June 08, 2016
Iterative Deepening Question by David Cimbalista, CCC, July 23, 2016 » Iterative Deepening
Aspiration window with TT question by sandermvdb, OpenChess Forum, August 01, 2016 » Transposition Table

2016

Conceptual question on aspiration windows by Jacob Wilkins, CCC, April 09, 2017
(I)ID and PV dropout by Harm Geert Muller, CCC, June 17, 2017 » Fail-Low, Internal Iterative Deepening, Iterative Deepening
Aspiration window problem by Sander Maassen vd Brink, CCC, October 30, 2017

External Links

References

^ Gerhard Hoehme - The Non-Euclidean Window (1964), mixed technique / wood on canvas, Art Museum, Bochum, North Rhine-Westphalia, Germany, part of The Industrial Heritage Trail of the Ruhr area, Photo by Gerd Isenberg, October 30, 2016

What links here?

Page	Date Edited
Abyss	Aug 5, 2017
Alarm	Jun 7, 2017
Alberto Sanjuan	Nov 3, 2014
AliBaba	Aug 17, 2014
Alpha-Beta	Jan 28, 2018
Amoeba	Mar 19, 2018
Amundsen	Sep 3, 2013
Andrew Grant	Jan 13, 2018
Android-Chess	Jun 2, 2016
Andscacs	Jan 16, 2018
Arion	Nov 28, 2014
Aspiration Windows	Nov 1, 2017
Atlas (ESP)	Jan 28, 2018
Bas Hamstra	Feb 4, 2018
Belzebub	Oct 20, 2015
Beowulf	May 5, 2017
BigLion	Sep 28, 2016
Bison	Sep 29, 2016
Bobcat	Jun 27, 2017
Brainless	Jun 24, 2017
Carballo	Oct 2, 2016
Celes	May 23, 2014
Cheese	Feb 17, 2018
Cheiron	Jan 7, 2016
Chenard	Sep 5, 2015
Cheng	Jul 30, 2017
Chess 0.5	Nov 20, 2016
chess22k	Apr 23, 2018
ChessBrainVB	Jun 24, 2017
Chessterfield	Sep 29, 2016
Chezzz	Jan 20, 2013
Cinnamon	Sep 23, 2017
Claudia	Jun 1, 2016
Clubfoot	Sep 8, 2015
Coiled	Mar 12, 2017
Comet	Jan 8, 2016
Critter	Jan 25, 2014
CuckooChess	Jan 17, 2017
Cupcake	May 19, 2016
DanaSah	Oct 9, 2017
David B. Weller	Sep 13, 2015
DayDreamer	Aug 22, 2016
Demolito	Mar 1, 2018
Deuterium	Jun 23, 2014
Diablo	May 17, 2016
DiscoCheck	Jun 23, 2017
Djinn	Feb 8, 2016
Don Dailey	Dec 7, 2016
Donna	Aug 17, 2017
DrunkenMaster	Nov 1, 2016
Dumb	Mar 10, 2018
Ethereal	Mar 20, 2018
Eveann	Apr 3, 2017
Exact Score	Dec 28, 2012
Fail-High	Oct 22, 2017
Fail-Low	Jun 23, 2017
FCP	Jun 15, 2013
Fischerle	Aug 21, 2017
Fixafan	Oct 2, 2015
Fizbo	Dec 22, 2017
Flux	Jan 12, 2016
Fortress (Engine)	Oct 19, 2017
Francesca	Jan 7, 2016
Freyr	Mar 6, 2014
GambitVB	Oct 24, 2016
Garbochess-JS	Sep 23, 2017
Gaviota	Jan 21, 2018
GES	Sep 13, 2015
Gibbon	Dec 23, 2014
Ginkgo	Jul 13, 2016
Gk	Oct 9, 2017
Gogobello	Jul 30, 2017
GullChess	Jun 27, 2017
Gunnar Harms	Feb 15, 2013
Hagrid	Apr 12, 2016
Hakkapeliitta	Apr 26, 2016
HAL	Jun 14, 2016
Harm Geert Muller	Mar 31, 2018
HeavyChess	Feb 14, 2014
Horizon	Mar 17, 2013
Internal Iterative Deepening	Feb 5, 2018
Iterative Deepening	Jun 23, 2017
Jan Renze Steenhuisen	Sep 10, 2017
Jens Bæk Nielsen	Mar 3, 2015
JikChess	Nov 29, 2015
Joachim Rang	Mar 19, 2014
Joanna	Dec 9, 2014
Joker IT	Sep 16, 2017
Kaissa	Apr 9, 2018
Kanguruh	Jan 13, 2013
Kholin	Jan 3, 2018
King of Kings	Sep 4, 2013
KnockOut	Sep 20, 2016
Leftmost Node	May 28, 2011
List (Program)	Jan 7, 2016
MadChess	Jul 4, 2017
Martin Bauer	Apr 3, 2013
Marvin	Feb 10, 2018
Matilde	Jan 1, 2014
Matthew R. Brades	Jun 9, 2017
Mediocre	Feb 27, 2015
MessChess	Mar 6, 2014
Minimax (program)	Dec 27, 2013
Move Ordering	Feb 27, 2018
MTD(f)	Jul 17, 2017
Napoleon	Jun 25, 2017
Natwarlal	Aug 26, 2013
Nemorino	Dec 21, 2017
Nesik	Jan 24, 2014
Neurosis	Dec 23, 2017
Nirvanachess	Sep 30, 2017
NoraGrace	Nov 23, 2014
Null Window	Nov 8, 2016
Nullmover	Jul 21, 2013
Occam	Jan 21, 2016
Octochess	Aug 15, 2017
OliThink	May 19, 2017
Orion	Oct 15, 2017
Paladin	Jan 29, 2017
Pawny	Jun 17, 2015
Phalanx	May 2, 2016
Pharaon	Sep 2, 2017
PolarChess	May 15, 2017
Popochin	Feb 5, 2016
Principal Variation Search	Oct 22, 2017
Prophet	Sep 30, 2017
Protector	Oct 12, 2017
Protej	Jul 27, 2014
PVS and aspiration	Oct 8, 2014
Querg	Dec 11, 2013
Rabbit	Oct 5, 2014
RDChess	May 3, 2013
RedQueen	Nov 13, 2017
Requiem	Feb 5, 2018
Reza Shams	Oct 31, 2016
Rodent	Jan 11, 2018
RomiChess	Jan 2, 2018
Root	Sep 26, 2016
Russell Reagan	Aug 31, 2013
Sayuri	Oct 1, 2017
Scidlet	May 31, 2014
Search	Feb 1, 2018
Search Explosion	Mar 30, 2017
Search Instability	May 5, 2017
Search Statistics	Jan 16, 2018
Senpai	Nov 10, 2017
Sharper	Jun 6, 2017
Shield	May 17, 2017
Simplex	Mar 6, 2016
Sinobyl	Jul 3, 2014
Sjeng	Aug 17, 2017
Slow Chess	May 17, 2016
Small Potato	Feb 14, 2014
SmarThink	Feb 2, 2018
Snitch	Apr 7, 2016
Soldat	Aug 20, 2017
Stockfish	Apr 7, 2018
Sune Fischer	Apr 7, 2014
Sunsetter	Jun 1, 2017
Sven Schüle	Sep 20, 2016
Tao	Jan 8, 2016
Tech	Apr 20, 2018
TechMate	Aug 23, 2014
Teki	Mar 29, 2018
Texel	Oct 9, 2017
The Turk (TR)	Apr 1, 2017
Thor's Hammer	Nov 23, 2013
Tornado	Dec 14, 2017
TRACE	Feb 14, 2013
Transposition Table	Apr 19, 2018
Triangular PV-Table	Jun 12, 2017
Tucano	Dec 16, 2017
Vanilla Chess	Jan 13, 2013
Warrior	Feb 23, 2015
Wasp	Nov 24, 2017
Waxman	Aug 18, 2014
Window	Jun 7, 2017
Wing	Oct 26, 2017
Woodpusher	Dec 12, 2016
WyldChess	Mar 10, 2018
Xiphos	Apr 22, 2018
Xpdnt	Sep 13, 2015
ZChess	Jan 8, 2016
Zeus RU	Jun 6, 2015
Ziggurat	Oct 9, 2017
Zurichess	Mar 12, 2018

Up one level

Asymmetric evaluation

GerdIsenberg — Thu, 17 Nov 2016 09:02:03 GMT

Home * Evaluation * Asymmetric evaluation

		Some programs score certain terms differently for the side they are playing and for the opponent. Most often the big terms, like king safety, passed pawn evaluation or mobility are scaled in some way. Whilst it might be argued that this idea runs counter the definition of chess as a zero-sum game, it also allows greater freedom in shaping the program's playing style. Richard Lang's programs were famous for their asymmetry in evaluation and forward pruning ^[1] , which emphasis safety (rules like 'do not start a wild attack, but worry a lot if the opponent does so') ^[2] .
Henry Moore - Helmed Head N° 2 ^[3]

Publications

Ingo Althöfer (1992). On Asymmetries in Chess Programs. ICCA Journal, Vol. 15, No. 1
Javier Ros Padilla (1994). Estimating Asymmetry and Selectivity in Chess Programs. ICCA Journal, Vol. 17, No. 1 ^[4]

Forum Posts

1997 ...

asymmetry by Andrew Tridgell, rgcc, August 12, 1997 » KnightCap, Parity Pruning
Re: Junior's long lines: more data about this... by Don Dailey, CCC, December 26, 1997
Genius' asymmetric-search by example: TRY yourself by Thorsten Czub, rgcc, December 30, 1997
Asymetric king safety by Tom King, rgcc, March 13, 1999

2000 ...

Parity of depth level and evaluation by Claude Le Page, CCC, June 13, 2005

2010 ...

evaluating color agnostic terms by Alvaro Cardoso, CCC, October 15, 2013
Different eval for white/black by Matthew Lai, CCC, January 05, 2015
Asymmetrical evaluation by Laurie Tunnicliffe, CCC, May 24, 2016 » Odd-Even Effect
Symmetrical evaluation and endgame by Hamfer, OpenChess Forum, June 02, 2016 » Tempo

References

^ Genius' asymmetric-search by example: TRY yourself by Thorsten Czub, rgcc, December 30, 1997
^ Kaare Danielsen (1987). The 7th World Microcomputer Chess Championship, Rome, Italy, September 14-20, 1987. ICCA Journal, Vol. 10, No. 3 » WMCCC 1987
^ Henry Moore - Helmed Head N° 2 (1950), Bronze on Marble slab, Art Museum, Bochum, North Rhine-Westphalia, Germany, part of The Industrial Heritage Trail of the Ruhr area, Photo by Gerd Isenberg, October 30, 2016, see also 2011 image of the sculpture at Art Gallery of New South Wales from Wikimedia Commons
^ ICCA Journal, Vol. 17, No. 1 by Jos Uiterwijk, rgcc, May 02, 1994

What links here?

Page	Date Edited
Alvaro Cardoso	Jan 12, 2018
Andrew Tridgell	Aug 3, 2015
Asymmetric evaluation	Nov 17, 2016
Evaluation	Feb 1, 2018
Glass	May 24, 2017
Hossa	Jan 7, 2016
Javier Ros Padilla	Sep 2, 2015
KnightCap	Nov 6, 2016
Laurie Tunnicliffe	Jun 13, 2017
Matthew Lai	Dec 6, 2017
Mephisto Roma	Sep 1, 2017
Odd-Even Effect	May 19, 2017
Opponent Model Search	Aug 14, 2017
Parity Pruning	Jan 14, 2013
Psion	Mar 20, 2017
Richard Lang	Jan 7, 2016
Tempo	Jan 17, 2018
Tom King	Aug 19, 2017

Up one Level

Auto232

GerdIsenberg — Sun, 25 Feb 2018 21:07:16 GMT

Home * Protocols * Auto232

		Auto232, an autoplayer protocol based on the serial communication RS-232 standard. It was initially developed by Chrilly Donninger in the mid 90s to communicate with the Chess 232 Board. A MS-DOS TSR driver, available for various chess programs, was able to "hook" into their printer output to parse their moves played, and to redirect input and commands into the keyboard buffer to start new games and enter moves. With two PCs, or two COM ports even with one computer ^[1], connected by a modified null-modem cable, it was now possible to play matches between two programs automaticly, a huge relief for testers and engine rating list organizations like SSDF. The Auto232 product with cable and software was purchased by CSS-Shop and Gambit-Soft.
Zauberlehrling ^[2]

Windows

A free Windows Auto232 driver written by Stefan Meyer-Kahlen ^[3] allowed automatic play also between Windows programs. Auto232 was further incorporated inside various GUIs and engines, but implementations were at times buggy and the protocol not that reliable specially concerning game termination ^[4]. With the advent and wider distribution of the standardized computer chess protocols such as the Chess Engine Communication Protocol aka WinBoard / XBoard and the Universal Chess Interface, Auto232 became obsolete and outdated.

Publications

Chrilly Donninger (1996). Zauberlehrling - Das Auto232-Protokoll im Detail. CSS 1/96, pdf (German) ^[5]

Forum Posts

1997 ...

Technische Spezifikation des 232-Protokolls (German) by Harald Faber, rgcc, January 08, 1997
Windows driver for CHESS 232 board an Autoplayer 232 by Bert Seifriz, CCC, November 09, 1997

1998

AUTO232 question by Amir Ban, CCC, March 01, 1998
Smartboard, Auto232 by Stuart Cracraft, CCC, February 14, 1998
Kill this auto232-players by Peter Herttrich, CCC, April 29, 1998
Survey proposal: Importance of Auto232 compatibility by Moritz Berger, CCC, September 09, 1998
Autoplayer for Win32 (again) by Stefan Meyer-Kahlen, CCC, September 12, 1998
Auto232 by Chris Whittington, rgcc, September 12, 1998
Autoplayers and Bean-Counters by Chris Whittington, rgcc, October 18, 1998

1999

AUTO232 and memory protection by Ed Schröder, CCC, February 03, 1999
Re: Auto232 questions, here is the manual in English! by Harald Faber, CCC, April 07, 1999
Re: What Is Auto232? by Harald Faber, CCC, April 23, 1999
Re: my own auto232 player by Vincent Diepeveen, CCC, December 07, 1999

2000 ...

Re: Auto232 with one machine? by Stefan Meyer-Kahlen, CCC, January 29, 2000
end of auto232? by Harald Faber, CCC, March 03, 2000
Definition of the Extended Autoplayer 232 Protocol by Stefan Meyer-Kahlen, CCC, May 16, 2000
Auto232, and one computer by Peter Skinner, CCC, August 18, 2000
Auto232 - Anyone with a good source of info on how to use it? by Steve Maughan, CCC, November 17, 2000
Auto232 using a network by Fabio Barrettone, CCC, July 17, 2001
how to run auto232 with 1 pc by Mustafa, CCC, May 28, 2002
auto232 by Christophe Drieu, CCC, October 23, 2002
Auto232 1.0 revisited by Michael P. Nance Sr., CCC, September 27, 2003
auto232 without null modem cable by Vasik Rajlich, CCC, April 18, 2004

2005 ...

Chess programs using Auto232 by Olivier Deville, CCC, September 06, 2005
Auto232 with only USB ports (solution?) by James T. Walker, CCC, January 04, 2006
How do I connect using auto232 to ICC using Fritz GUI? by LJC, CCC, June 14, 2009

2010 ...

Eberhard Boerger's Auto232 adaptor/Remi Coulom's Auto232 by Sedat Canbaz, CCC, March 06, 2014
Auto232 Driver for DOS (and Windows?) by Theo Heinze, CCC, July 11, 2015

External Links

Auto232 player - Auto232 and Winboard by Aaron Tay, hosted by Ron Murawski
Schachclub Leinzell - Autoplayer 232 by Peter Schreiner, May 2000 (German)

References

^ Auto232, and one computer by Peter Skinner, CCC, August 18, 2000
^ Zauberlehrling (The Sorcerer's Apprentice) by Inges Idee - a 35 meter steel tower like a dancing electricity pylon, installed at Emscherkunst art exhibition 2013 near Haus Ripshorst, Gasometer Oberhausen in the background, Oberhausen, Germany, The Industrial Heritage Trail, Image by Gerd Isenberg, October 11, 2015
^ Windows driver for CHESS 232 board an Autoplayer 232 by Bert Seifriz, CCC, November 09, 1997
^ Re: Auto232 - Anyone with a good source of info on how to use it? by Robert Hyatt, CCC, November 17, 2000
^ The Sorcerer's Apprentice (Zauberlehrling) from Wikipedia

What links here?

Page	Date Edited
Auto232	Feb 25, 2018
Chess 232 Board	Jun 19, 2016
Chrilly Donninger	Dec 19, 2016
Ed Schroder	Feb 26, 2018
Engine Rating Lists	Dec 13, 2017
Moritz Berger	Feb 25, 2018
Olivier Deville	Sep 29, 2016
Patzer	Apr 5, 2017
Protocols	Jan 20, 2018
Queue	Apr 4, 2017
Stefan Meyer-Kahlen	Jun 19, 2017

Up one Level

Candidates (Bitboards)

GerdIsenberg — Sat, 11 Nov 2017 09:57:18 GMT

Home * Board Representation * Bitboards * Pawn Pattern and Properties * Candidates

		Candidates, pawns that can force themselves to become passed pawns simply with a series of pawn moves. Candidates are half-open pawns with no mechanical but dynamical obstructions. Specifially, the pawn must be on a half-open file, and the number of defender pawns that can help the pawn advance are greater than or equal to the number of pawns which attack the pawn or squares in front of it.
Samuel Bak - The Designated ^[1]

Candidate and Faker

While the intersection of the frontspan with opposing pawns is empty, the intersection of front attackspans with opposing pawns is not (otherwise it would already a passer). The opposing pawns as member of the front attackspan(s), stand sentinel over one or more squares in the frontfill of the open pawn, and are about to capture the open pawn, if it may advance into - or already is - a lever. Those opposing pawns are called sentries.

If the open pawn has one or more helper-pawns on adjacent files, which are able to recapture the sentry, the candidate is a real one and is guaranteed to force a passer. Otherwise, without enough support from helpers, the candidate is only a faker.

The following diagrams shows advanced candidates and fakers, assuming black to move:

candidates b6, f4   fakers -
sentries   c7, g2   more sentries
helper     c5, g4   than helpers
. . . . | . . .     . . . . | . . .
. . b . . . . .     b . b . . . . .
. w . . . . . .     . w . . . . . .
. . w . . . . .     . . w . . . . .
. . . . . b b .     . . . . . b b .
. . . . . . . .     . . . . . . . .
. . . . . . w .     . . . . w . w .
. . . | . . . .     . . . | . . . .

The white candidate on b6 is already in lever-distance with the sentry c7. The sentry c7 is likely forced to capture - otherwise b6 captures or pushes to become a passer. The white helper immediately recaptures and takes the role of the former candidate and becomes a passer. The black candidate on f4 can also force a passer. The helper on g4 compensates the sentry on g2. Usually, the candidate has to push forward, not the helper.

In the second diagram both candidates are pseudo-candidates or fakers, since there are more sentries than helpers - a7xb6 is required - otherwise, after c7xb6, c5-c6 would allow the helper to advance to a passer.

Advanced Candidates

Advanced candidates, already inside or about to enter the opponent side of the board are the most important to consider in evaluation. Even more if the interspan of sentries and helper is already one - and it is only about the control of the stop-square - or if the candidate is already part of a lever, the number of attacks and defenses.

In such cases, due to the forced nature of exchanging candidate, sentry and helper, only two or up to five plies are necessary to establish a passer. In fact those candidates may even be more worth than pawns already a passer - specially if the opponent king is outside the candidates square - or if the outside candidate may deflect the opponent king.

One may argue that a candidate already in lever distance with the sentry should be covered by quiescence search - since it is a capture/recapture sequence. Therefor more important to evaluate are the candidate-helper-duo/trio against one or two sentries, which is likely a kind of static exchange evaluation of the candidate's stop-square.

. . . . . . . .
. . s . . s . s   sentries
. . . . . . . .
. c h . . h c h   candidates with helpers
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .

To cover sets of advanced white candidates with attacked but sufficient defended stops already on the on the 5th rank, one may use some code like this. Feel free to introduce branches, e.g. if there are no white pawns on the fifth rank. Anyway, wSafePawnSquares might be used elsewhere, e.g. to decide whether helper pawns may advance to defend candidate's stop.

U64 wCandidatesOn5th(U64 wpawns, U64 bpawns) {
   const U64 rank5     = C64(0x000000ff00000000);
   U64 bPawnAnyAttacks = bPawnAnyAttacks(bpawns);
   U64 wSafeSquares    = wSafePawnSquares(wpawns, bpawns);
   U64 wSafeAttacked   = bPawnAnyAttacks  &  wSafeSquares;
   U64 blackFrontSpan  = (bpawns >> 8)    | (bpawns >> 16); // only for 5th rank
   return wpawns & rank5 &~blackFrontSpan & (wSafeAttacked >> 8);
}

Less Advanced

If it is about the long-term evaluation of telestop -squares - or the need of advancement of helper(s) to defend the stop-square, things become more complicated and one probably better relies on search and some general bonus to advance half-free pawns and advanced duos. Feel free to cover attackspan-related stuff for less advanced candidates respectively helpers and helper's helpers.

d4 is candidate     d4 is faker         d4 faker due to     d4 is candidate
                                        helper's sentry     due to helper's helper f2
. . . . . . . .     . . . . . . . .     . . . . . . . .     . . . . . . . .
. . s . s . . .     . . s . s . . .     . . s . s . . .     . . s . s . . .
. . . . . . . .     . . . . . . . .     . . . . . hs. .     . . . . . hs. .
. . . . . . . .     . . . . . . . .     . . . . . . . .     . . . . . . . .
. . . c . . . .     . . . f . . . .     . . . f . . . .     . . . c . . . .
. . . . . . . .     . . . . . . . .     . . . . . . . .     . . . . . . . .
. . h . h . . .     . . h . . . . .     . . h . h . . .     . . h . h hh. .
. . . . . . . .     . . . . . . . .     . . . . . . . .     . . . . . . . .

The Sneaker

Also known as a hidden passed pawn. A kind of candidate in disguise is an unfree pawn or faker that may become a passer through a sacrificial combination. In the diagram white may sacrifice the faker with b5-b6 - allowing black to establish a passer on b6 - but the sneaker on c6 becomes a much more advanced passer with a frontspan of only two against five:

. . . . . . . .
. . b . . . . .
. . w . . . . .
. w . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .
. . . . . . . .

A sneaker is likely advanced (opponent side of the board), rammed and defended, but no lever. No other opposing pawn controls it's stop or telestop squares.

External Links

Pawn Power in Chess by Hans Kmoch - Glossary of Terms - Chess Forums - Chess.com ^[2]
Candidates Tournament from Wikipedia
Jango Edwards - Harry Christmas, September 10, 2009, Zeche Carl ^[3], Essen, YouTube Video

References

^ Chess in the Art of Samuel Bak, Center for Holocaust & Genocide Studies, University of Minnesota
^ Hans Kmoch (1959, 1990). Pawn Power in Chess. New York: Dover, 1990. Previous ed.: New York: McKay, 1959. ISBN 0-486-26486-6
^ Zeche Carl is part of The Industrial Heritage Trail

What links here?

Page	Date Edited
Attack Spans	Mar 4, 2010
Backward Pawns (Bitboards)	May 5, 2017
Candidate Passed Pawn	Nov 11, 2017
Candidates (Bitboards)	Nov 11, 2017
Faker	Nov 11, 2017
Hans Kmoch	Nov 11, 2017
Hidden Passed Pawn	Nov 11, 2017
Murka	Nov 11, 2016
Passed Pawns (Bitboards)	Aug 23, 2010
Pawn Attacks (Bitboards)	Mar 4, 2010
Pawn Pattern and Properties	Nov 11, 2017
Pawn Spans	Jul 22, 2010
PawnKing	Sep 5, 2014

Up one Level

Coiled

GerdIsenberg — Sun, 12 Mar 2017 19:07:44 GMT

Home * Engines * Coiled

		Coiled, an UCI compliant chess engine by Oscar Gavira, written in C, first released in 2013. Coiled 0.4, released in September 2016 is available as 32-bit and 64-bit executable for Windows ^[1].
Slinky Springs to Fame ^[2]

Features

^[3]

Board Representation

Search

Evaluation

Misc

Forum Posts

Hispanic chess engines + Winboard Zeta Pack number 18 by Pedro Castro, CCC, August 14, 2013
Coiled 0.2b by Oscar Gavira, CCC, July 22, 2014
Coiled 0.4 by Oscar Gavira, CCC, September 12, 2016

External Links

Chess Engine

Coiled - Información y descargar. Motor de ajedrez UCI (Spanish)
Coiled in CCRL 40/4

Misc

References

^ Coiled 0.4 by Oscar Gavira, CCC, September 12, 2016
^ Slinky Springs to Fame designed by Tobias Rehberger, Rhine–Herne Canal, Gasometer Oberhausen in the background with Wonders of Nature exhibition, Oberhausen, Germany, The Industrial Heritage Trail, Image by Gerd Isenberg, March 12, 2017, see also Image by Frank Vincentz, November 29, 2012, Category:Slinky Springs to Fame from Wikimedia Commons,
^ Based on Coiled - Técnicas utilizadas

What links here?

Page	Date Edited
Coiled	Mar 12, 2017
Engine releases	Apr 23, 2018
Engines	Mar 10, 2018
Loop (Program)	Mar 14, 2017

Up one level

Elephant

GerdIsenberg — Mon, 19 Sep 2016 19:31:53 GMT

Home * Engines * Elephant

		Elephant, a WinBoard compatible chess engine written by Harald Lüßen in C++, first released in March 2004 ^[1] . The name was chosen due to the connection with pieces in Chaturanga, Chinese Chess and chess, such as rook and bishop ^[2] , because elephants are known to be intelligent, and further due its author's weight ^[3] .
The Glas Elephant ^[4] in Hamm ^[5]

Description

Elephant applies PVS alpha-beta with transposition table, quiescence, adaptive null move pruning, IID, razoring, futility pruning and various extensions, embedded inside an fractional ply iterative deepening framework. Move ordering at the root is based on node count, and otherwise considers hash move including principle variation, static exchange evaluation, killer- and history heuristic. Evaluation might be lazy and takes material, cached pawn structure, king safety, piece-squares tables, mobility and multiple other terms into account. Elephant was used as testbed to compare various bitboard techniques in generating sliding piece attacks ^[6], in particular Exploding- and Sherwin Bitboards.

Forum Posts

Elephant 1.00, a new winboard engine by Harald Lüßen, CCC, March 15, 2004
Elephant and pondering by Olivier Deville, CCC, April 11, 2004 » Pondering

External Links

Chess Engine

Elephant from WBEC Ridderkerk
Elephant 1.06 in CCRL 40/4

Chess and Variants

Indian Chess Sets
Chaturanga from Wikipedia
Xiangqi - Pieces from Wikipedia
Elephant Gambit from Wikipedia
Elephant, the Chinese Chess engine by Shun-Chin Hsu, Shun-Shii Lin, Shih-Chieh Huang et al.

Misc

Elephant from Wikipedia
Elephant (disambiguation) from Wikipedia
Blind men and an elephant - Wkipedia
War elephant from Wikipedia
King Crimson - Elephant Talk, live on Fridays (1982), YouTube Video
lineup: Tony Levin, Adrian Belew, Bill Bruford, Robert Fripp

References

^ Elephant from WBEC Ridderkerk
^ Re: Elephant by Eugene Nalimov, CCC, March 26, 2001
^ Elephant 1.00, a new winboard engine by Harald Lüßen, CCC, March 15, 2004
^ The Glas Elephant, Maximilianpark, Hamm, North Rhine-Westphalia, Germany, The Industrial Heritage Trail
^ Elefantenparade – HammWiki
^ Re: BitBoard Tests Magic v Non-Rotated 32 Bits v 64 Bits by Harald Lüßen, CCC, August 24, 2007

What links here?

Page	Date Edited
Alfil	Sep 3, 2015
Elephant	Sep 19, 2016
Engines	Mar 10, 2018
Exploding Bitboards	Mar 9, 2015
Hannibal	Oct 4, 2017
Harald Lüßen	Mar 20, 2013
Jumbo	Dec 19, 2017
Pondering	Dec 9, 2017
Sherwin Bitboards	Mar 20, 2013

Up one Level

Fritz

GerdIsenberg — Mon, 26 Feb 2018 11:33:20 GMT

Home * Engines * Fritz

		Fritz (early versions called Knightstalker in the USA), a series of chess programs published by ChessBase, until Fritz 13 the engine developed by primary author Frans Morsch and Mathias Feist, Deep Fritz 14 released in November 2013 by Gyula Horváth ^[1], and Fritz 15 in November 2015 by Vasik Rajlich ^[2] ^[3]. Fritz 1-13 were based on Frans Morsch's program Quest, and was first marketed by ChessBase in 1991 as MS-DOS program with its own Graphical User Interface ^[4] . Since version 4, released in 1996, Fritz ran on Windows, and is until today one the world’s most popular and successful chess programs. At the WCCC 1995, Fritz became World Computer Chess Champion, winning a notable game versus Deep Blue prototype ^[5] and the playoff ^[6] against Star Socrates.
Unser Fritz 2/3, protego sundial and machine hall ^[7]

Etymology

The given name Fritz originated as a German nickname for Friedrich, or Frederick (der "Alte Fritz" was a nickname for King Frederick II of Prussia, and of Frederick III, German Emperor ^[8]), as well as for similar names including Fridolin. Fritz was also a name given to German troops by the British and others in the first and second world wars, equivalent to Tommy, as the British troops were called by German and other troops ^[9] . Creative ChessBase partner Olaf Oldigs ^[10] had suggested the name Fritz for the chess program ^[11] .

Selected Games

WCCC 1995, round 5, Deep Blue Prototype - Fritz ^[12]

[Event "WCCC 1995"]
[Site "Chinese University HKG"]
[Date "1995.05.29"]
[Round "5"]
[White "Deep Blue Prototype"]
[Black "Fritz"]
[Result "0-1"]
 
1.e4 c5 2.Nf3 Nc6 3.d4 cxd4 4.Nxd4 Nf6 5.Nc3 e5 6.Ndb5 d6 7.Bg5 a6 8.Na3 b5
9.Bxf6 gxf6 10.Nd5 f5 11.Bd3 Be6 12.Qh5 f4 13.O-O Rg8 14.Kh1 Rg6 15.Qd1 Rc8
16.c4 Qh4 17.g3 Qh3 18.Qd2 f3 19.Rg1 Rh6 20.Qxh6 Qxh6 21.cxb5 Bxd5 22.exd5
Nb4 23.Bf5 Rc5 24.bxa6 Nxa6 25.Nc2 Qd2 26.Ne1 Rxd5 27.Nxf3 Qxf2 28.Be4 Ra5
29.Rg2 Qe3 30.Re1 Qh6 31.Bc6+ Kd8 32.a3 f5 33.Rc2 Rc5 34.Rxc5 Nxc5 35.Rf1
Be7 36.a4 f4 37.gxf4 Qxf4 38.Rg1 Nxa4 39.b4 Qxb4 0-1

Null Move

Frans Morsch, as well as other Dutch computer chess programmers like Bart Weststrate and Dap Hartmann ^[13] , did early experiments with recursive null move pruning in the late 80s, likely after it was discussed at the panel workshop during the WCCC 1986 after Don Beal's talk covering null move ^[14] ^[15] . Frans Morsch told Chrilly Donninger about recursive null move, who popularized it by his Null Move and Deep Search paper in the ICCA Journal 1993 ^[16] .

Descriptions

from the ICGA tournament page ^[17] :

1995

Fritz is built around a selective search technique known as null-move search. As part of its search, Fritz allows one side to move twice (the other side does a null-move). If the position after the null-move does not return a high value in the evaluation function, then clearly the first of the two moves did not contain a threat. This applies to 95% of the moves in a search. Detecting such moves before they are searched to the full depth is an excellent method to speed-up the search. In its latest version, Fritz manages a 10-times speed-up over a version without the null-move search. Selective search unavoidably introduces oversights, but these are few. In tournaments against humans and other programs, Fritz has proven to be a tough opponent when defending difficult positions.

1997

Fritz won the ICCA chess computer world championship in Hong Kong 1995 beating a prototype of the Deep Blue chess computer. It obtained the best computer result in the 1996 man-computer Aegon tournament. Fritz is build around a selective search technique known as the null-move search. Move generators, evaluation functions and data structures have been designed specially to maximise the effectiveness of the null-move search. If anything, Fritz is fast. The search engine is written in highly optimised assembly language. The present version searches at a rate of one thousand processor cycles per position. The openings book was constructed from grandmaster games. Fritz learns from his games and adjusts the probability weights in the openings book automatically.

1999

Fritz is build around a selective search technique known as the null-move search. As part of its search, Fritz allows one side to move twice (the other side does a null-move). This allows the program to detect weak moves before they are searched to their full depth. Move generators, evaluation functions and data structures have been designed to maximize the effectiveness of the null-move search. Fritz is the winner of the previous computerchess world championship in Hong Kong 1995. 1993 Fritz tied for 1st place in a Blitz tournament in Munich with the complete world elite. It scored the best computer result in the 1996 man-computer Aegon tournament. In 1998 Fritz was leading the prestigious Swedish rating list. It won an active chess tournament Frankfurt 1998 with a full point ahead of 36 grandmasters.

Deep Fritz

Deep Fritz is the engine designed for multiprocessing and parallel search, it first appeared as Deep Fritz 6 in 2000. Since version 14 by Gyula Horváth, Deep is obligatory.

Fritz SSS

A Fritz version called SSS ^[18] or even SSS* ^[19] that played the Dutch Chess Championship 2000 in Rotterdam, becoming third with 7/11 behind Loek van Wely, and Jeroen Piket, shared with Sergei Tiviakov and Paul van der Sterren ^[20], was not related to the SSS* search algorithm, but to the three primary sponsors of the event ^[21] ^[22].

Pocket Fritz

Pocket Fritz is a chess program for PocketPC Personal digital assistants (PDAs). Pocket Fritz 4 is based on Hiarcs by Mark Uniacke, Pocket Fritz 2 used a port of Shredder by Stefan Meyer-Kahlen ^[23] .

Fritz User Interface

Fritz 1

The original Fritz MS-DOS Graphical User Interface from 1991 ^[24]

Fritz 5

Fritz 5 Windows Graphical User Interface ^[25]

Deep Fritz 14

Recent Deep Fritz GUI is suited to run other ChessBase or UCI engines with either using its own proprietary protocol, as well as the UCI protocol.

Deep Fritz 14 GUI ^[26]

Authors

Book Authors

Release Dates

Frans Morsch

Fritz 1.0 : 1991
Fritz Deluxe : 1992
Fritz 2.0 : 1992 or 1993
Fritz 2.51 : 1994
Fritz 3.0 : 1994 or 1995
Fritz 4.0 : 1995 or 1996
Fritz 5.0 : 1997 or 1998
Fritz 5.32 : 1998 or 1999
Fritz 6 : 2000
Deep Fritz : 2000
Fritz 7 : July 2001
Fritz Bahrain : November 2002
Deep Fritz 7.0 : 2003
Fritz 8 : September 2003
X3D Fritz : November 2003
Fritz 8 Bilbao : December 2004
Deep Fritz 8.0 : 2005
Fritz 9 : December 2005
Fritz 10 : October 2006
Deep Fritz 10 : December 2006
Fritz 11 : November 2007
Deep Fritz 11 : November 2008
Fritz 12 : October 2009
Deep Fritz 12 : July 2010
Fritz 13 : October 2011
Deep Fritz 13 : June 2012

Gyula Horváth

Deep Fritz 14 : November 2013

Vasik Rajlich

Fritz 15 : November 2015
Fritz 16 : November 2017

Matches

Publications

Fabian Mäser (1995). Fritz vs.Deep Blue: Opening Book vs, Opening Book. Computer Chess Reports, Vol. 5, No. 2, pp. 22 » WCCC 1995
Robert Hyatt (1995). Still more Fritz vs. Deep Blue: Opening Book vs, Opening Book. Computer Chess Reports, Vol. 5, No. 2, pp. 22
Larry Kaufman (1995). Does Fritz deserve to be World Champion? Selective Search 60, pp 3, pdf hosted by Mike Watters
Karsten Müller (2002). The Clash of the Titans: Kramnik – Fritz Bahrain. ICGA Journal, Vol. 25, No. 4 » Kramnik versus Deep Fritz 2002
Matthias Wüllenweber (2002). The Match from Fritz' View Point. ICGA Journal, Vol. 25, No. 4
David Levy (2003). Kasparov vs X3D Fritz. ICGA Journal, Vol. 26, No. 4 » Kasparov versus X3D Fritz 2003
Christian Liebert (2005). Fritz 9: Der König ist zurück. Computerschach und Spiele Online, pdf (German)
Christian Liebert (2006). Fritz die Zehnte. Computerschach und Spiele Online, pdf (German)
Matthias Wüllenweber, Frederic Friedel, Mathias Feist (2006). Kramnik vs. Deep Fritz 10: Computer wins match by 4-2. ICGA Journal, Vol. 29, No. 4 » Kramnik versus Deep Fritz 2006
Eric Hallsworth (2007). Vladimir Kramnik (World Champion) v Deep Fritz 10. Selective Search 128, pp. 14-24, pdf hosted by Mike Watters

Forum Posts

1991 ...

Commercial Chess Programs by Mike Valvo, rgc, July 19, 1991 » ChessMachine, MChess, Zarkov
KnightStalker Demo by Benjamin Lin, rgc, December 29, 1992
ChessBase for Windows and/or Fritz 3 Review by Johannes Fürnkranz, rgc, September 06, 1994 » ChessBase (Database)
Fritz 3 ELO on different computers by Moritz Berger, rgc, September 19, 1994

1995 ...

Fritz 3 Makes IM Norm by Michel Behna, rgc, January 31, 1995
Deep Thought /WCCC Round 5 vs Fritz by Robert Hyatt, rec.games.chess, May 31, 1995 » WCCC 1995
Fritz 4 and the SSDF by Moritz Berger, rgcc, June 27, 1996 » SSDF
LCT II results of Reb9, F5, and H6 on K6/233 by Albert Silver, CCC, January 03, 1998 » LCT II, Rebel, Hiarcs
Fritz 5 by Didzis Cirulis, CCC, February 06, 1998
Multi-Fritz with Boss versus IM R. Vasquez by Ingo Althöfer, CCC, March 09, 1999 ^[27]
Tactical monsters: Fritz5.32 and Goliath 2.05 by Jouni Uski, CCC, August 03, 1999

2000 ...

How make Fritz execute brute force search? by Leonid, CCC, July 26, 2000
Junior chess program. Just version of Fritz 5? by Leonid, CCC, July 29, 2000 » Junior
Re: Fritz protocol by Odd Gunnar Malin, Winboard Forum, April 14, 2002 » Wb2UCI
Re: Something new about Fritz? English by Sven Reichard, CCC, June 23, 2002
Re: Something new about Fritz? English, part 2 by Sven Reichard, CCC, June 24, 2002 » Eduard Nemeth
Request for link to Eduard Nemeth messages about Fritz 8.0.0.23 by Javier Ros Padilla, CCC, March 17, 2003 » Eduard Nemeth
Re: Shredder 8 secret: search depth? by Vasik Rajlich, CCC, March 23, 2004 » Depth, Shredder, Junior

2010 ...

Fritz 12 by Alexander Schmidt, CCC, May 31, 2011
Fritz and Naum shown as Rybka/Strelka clones by Kai Laskos, CCC, October 17, 2011
Deep Fritz 11 eval by BB+, OpenChess Forum, October 23, 2011
Are Fritz and Naum Rybka/Strelka clones? by SR, Rybka Forum, November 09, 2011
New Fritz author? by John Hartmann, CCC, November 19, 2013
Re: New Fritz author? by Albert Silver, CCC, November 20, 2013
Re: First Impressions (Deep Fritz 14)? by Albert Silver, CCC, November 22, 2013
Allegations that Deep Fritz 14.... by Dr.Wael Deeb, CCC, Engine Origins, December 03, 2013
Fritz 11 by Rebel, OpenChess Forum, December 10, 2013 ^[28]
ChessBase / Fritz interface running on Ubuntu? by Norbert Raimund Leisner, CCC, December 17, 2013 » Linux

2015 ...

Fritz 15 (Vas Rajlich?) by Graham Banks, CCC, July 24, 2015 » Vasik Rajlich
Fritz 15.0 by Tim Shackel, CCC, November 20, 2015
"Sampled search" ? by albitex, Rybka Forum, February 23, 2016
Fritz 16 by David Shanholtzer, CCC, November 12, 2017

External Links

Chess Engine

Purchase

ChessBase News

Fritz Defends to Draw Game 8 and the Match! Final Score: 4-4 The Brains in Bahrain Man-Machine match is over, from ChessBase News, October 19, 2002
Kasparov vs X3D Fritz match finishes 2-2 after game four draw from ChessBase News, November 19, 2003
Deep Fritz 8 review by Steve Lopez, ChessBase News, December 27, 2003
Mate search in Fritz by Steve Lopez, ChessBase News, August 07, 2004
Fritz 9 3D boards – part 1 by Steve Lopez, ChessBase News, January 10, 2006
Fritz 9 3D boards – part 2 by Steve Lopez, ChessBase News, January 17, 2006
Fritz 9 3D boards – part 3 by Steve Lopez, ChessBase News, January 25, 2006
Man vs machine shocker: Kramnik allows mate in one, Bonn, November 27, 2006
Kramnik vs Deep Fritz: Computer wins match by 4:2, ChessBase News, December 05, 2006
Deep Fritz 12 – an interview with the author, ChessBase News, February 17, 2010
Fritz 13 is now available – let's check who needs it!, ChessBase News, October 13, 2011
Deep Fritz 13 with blow-your-mind functions, ChessBase News, June 08, 2012
Deep Fritz 14: Faster, better, cheaper, ChessBase News, November 20, 2013
Deep Fritz 14 – Elo 3150 on your computer by Sean Marsh, ChessBase News, January 28, 2014
From Chess Challenger to Deep Fritz 14 by Ken Blake, ChessBase News, February 27, 2014 » Chess Challenger
Analyzing your games with Fritz (Part one) by Albert Silver, ChessBase News, June 02, 2014
Analyzing your games with Fritz (Part two) by Albert Silver, ChessBase News, June 04, 2014
Analyzing your games with Fritz (Part three) by Albert Silver, ChessBase News, June 07, 2014
Deep Fritz 14 now with ChessBase for Android by Albert Silver, ChessBase News, February 23, 2015 » Android
Using Deep Fritz 14 on a smartphone by A. Ganesan, ChessBase News, April 13, 2015 » Android
Come and get it – Fritz 15 released!, ChessBase News, November 25, 2015
Fritz 15 engine - questions and answers by Albert Silver, ChessBase News, January 04, 2016
Using your home chess engine anytime, anywhere by Albert Silver, ChessBase News, May 09, 2017
Fritz 16 – your companion and trainer, ChessBase News, November 12, 2017
Fritz 16 — a fun and instructive opponent by Albert Silver, ChessBase News, December 11, 2017

Rating Lists

Misc

References

^ New Fritz author? by John Hartmann, CCC, November 19, 2013
^ Fritz 15 - English Version, ChessBase Shop
^ Fritz 15 engine - questions and answers by Albert Silver, ChessBase News, January 04, 2016
^ Christmas dinner on a train – meet the ChessBase team from ChessBase News, December 23, 2003
^ Fabian Mäser (1995). Fritz vs. Deep Blue: Opening Book vs, Opening Book. Computer Chess Reports Vol. 5 No. 2 pp. 22, WCCC 1995
^ Shatin 1995, Chess, Round 6, Game 1
^ Former coal mine Unser Fritz 2/3 in Herne, North Rhine-Westphalia, Germany, now artist-studio, exhibition and event space, and part of The Industrial Heritage Trail of the Ruhr area - Image of protegohaube (flame arrester) as gnomon of a sundial and machine halls behind by Gerd Isenberg, bike tour, September 16, 2016. Unser Fritz/Crange is further district of Herne (Wanne), famous for its funfair Cranger Kirmes, and SV Unser Fritz the local chess club - eponym of the coal mine was Frederick III, German Emperor, see also Künstlerzeche Unser Fritz 2/3 - Chronik (German) and 2011 Image by Frank Vincentz
^ Der alte Fritz (1928) Wikipedia.de (German)
^ Fritz from Wikipedia
^ Olaf Oldigs - Google+
^ The ChessBase Christmas Party – part 1, ChessBase News, December 28, 2010
^ Shatin 1995, Chess, Round 5, Game 4
^ Chrilly Donninger (1994). Die Kunst des Nichtstuns. CSS 2/94, pdf (German)
^ Re: SOMA by Ed Schroder, CCC, August 26, 2009
^ Re: Search or Evaluation? by Mark Uniacke, Hiarcs Forum, October 14, 2007
^ Chrilly Donninger. (1993). Null Move and Deep Search: Selective-Search Heuristics for Obtuse Chess Programs. ICCA Journal, Vol. 16, No. 3, pp. 137-143
^ Fritz' ICGA Tournaments
^ Comp Fritz SSS chess games - 365Chess.com
^ Jaap van den Herik (2000). De toekomst van het schaaken. Schaakmagazine, 5/2000, pdf hosted by Hein Veldhuis
^ NED-ch 2000 - 365Chess.com Tournaments
^ Fritz SSS uses *SSS? by Bas Hamstra, CCC, May 15, 2000
^ Re: Fritz SSS uses *SSS? by Robert Hyatt, CCC, May 15, 2000
^ Chess Programs for Pocket PC and Palm devices by Dr. Axel Schumacher
^ Septober - Computerschach by Herbert Marquardt
^ Septober - Computerschach by Herbert Marquardt
^ Deep Fritz 14 from ChessBase
^ Rodrigo Vásquez Schroder - Wikipedia
^ Measuring similarity native ChessBase engines by Ed Schröder

What links here?

Page	Date Edited
3D Graphics Board	Sep 23, 2017
Aegon 1991	Mar 26, 2017
Aegon 1993	Mar 26, 2017
Aegon 1994	Mar 26, 2017
Aegon 1995	Apr 6, 2017
Aegon 1996	Jan 22, 2017
Aegon 1997	Apr 7, 2017
Albert Silver	Feb 25, 2018
Albrecht Heeffer	Sep 6, 2016
Alex Kure	Aug 27, 2016
Alexander Schmidt	May 17, 2016
Anaconda	Jul 4, 2015
Ananse	Jan 8, 2016
Android	Jan 9, 2018
AnMon	Nov 17, 2017
Aquarium	Dec 4, 2016
Arena	Mar 16, 2018
Atari ST	Dec 7, 2016
BikJump	Aug 11, 2014
Blondie25	Dec 7, 2017
Bobby	Jan 7, 2016
Bruce Moreland	Jan 20, 2016
Brute-Force	Jul 27, 2017
Brutus	Dec 24, 2016
Bryan Whitby	Jan 2, 2017
CCT Tournaments	Jan 29, 2017
CCT3	Feb 14, 2013
CCT4	Apr 22, 2013
Chess Tiger	Jan 7, 2016
ChessBase	Nov 25, 2017
ChessBase (Database)	Feb 26, 2018
Chessica	Nov 22, 2013
ChessMachine	Feb 26, 2018
ChessPartner	Nov 13, 2017
Cilkchess	Jan 21, 2016
Cock de Gorter	Nov 3, 2015
Connection Machine	Oct 12, 2016
CTG	Aug 22, 2016
Deep Blue	Aug 1, 2017
Deep Fritz versus Deep Junior 2007	Oct 15, 2016
Deep<9>	Nov 28, 2013
Depth	Feb 25, 2018
DGT Board	Feb 21, 2018
Didzis Cirulis	Dec 25, 2015
Diep	Jan 28, 2018
DOCCC 2001	Aug 15, 2015
Doctor?	Jun 7, 2016
Don Dailey	Dec 7, 2016
Eduard Nemeth	Nov 22, 2014
Eigenmann Endgame Test	Jun 1, 2017
Engine releases	Apr 23, 2018
Engines	Mar 10, 2018
Entering Moves	Sep 7, 2017
Eric Schiller	Dec 5, 2016
Federico Andrés Corigliano	Feb 13, 2014
Fischerle	Aug 21, 2017
Frans Morsch	Jun 23, 2017
Fridolin	Jun 27, 2017
Fritz	Feb 26, 2018
Fruit	Sep 27, 2016
GK 2100	Jun 11, 2016
Gromit	Apr 5, 2017
GUI	Mar 16, 2018
Gyula Horváth	Jan 7, 2016
Hagrid	Apr 12, 2016
Harvard Cup 1992	Mar 26, 2017
Hiarcs	Feb 25, 2018
ICGA Journal	Dec 21, 2017
ICT 2001	Oct 14, 2015
ICT 2002	Nov 19, 2016
ICT 2003	Aug 18, 2016
Ingo Althöfer	May 4, 2017
International CSVN Tournament	Jan 8, 2018
IPCCC	Jan 20, 2017
IPCCC 2000	Dec 21, 2012
IPCCC 2001	Jan 9, 2014
IPCCC 2002	May 31, 2014
IPCCC 2003	Aug 17, 2016
IPCCC 2004	Dec 1, 2014
IsiChess	Jan 7, 2016
Iweta Rajlich	Sep 23, 2017
Javier Ros Padilla	Sep 2, 2015
Johannes Fürnkranz	Feb 26, 2018
Jonny	Nov 4, 2017
Junior	Feb 27, 2018
Kai Laskos	Jan 21, 2018
Kasparov versus X3D Fritz 2003	Aug 17, 2016
King of Kings	Sep 4, 2013
Knowledge	Jul 22, 2017
Komodo	Mar 6, 2018
Kramnik versus Deep Fritz 2002	Oct 16, 2017
Kramnik versus Deep Fritz 2006	Nov 28, 2017
LCT II	Feb 25, 2018
Leonid Liberman	May 23, 2015
List (Program)	Jan 7, 2016
Man vs Machine Team Championship	Aug 21, 2016
Mathias Feist	Aug 27, 2016
MChess	Feb 26, 2018
Michael Valvo	Feb 26, 2018
Moritz Berger	Feb 25, 2018
Nimzo	Dec 30, 2017
Norbert Raimund Leisner	Jul 28, 2016
Novag Citrine	Aug 19, 2015
Novag Universal Electronic Chess Board	Feb 24, 2017
Now	Jan 7, 2016
Null Move Pruning	Dec 2, 2017
Oracle	Sep 4, 2016
Patzer	Apr 5, 2017
Peter Mysliwietz	Mar 5, 2017
Phalanx	May 2, 2016
Piece-Square Tables	Mar 31, 2018
PT 45	May 19, 2014
Quest	Mar 26, 2017
Rebel	Feb 25, 2018
Robert Hyatt	Dec 25, 2017
Rybka	Mar 27, 2017
Saitek Brute Force	Oct 9, 2015
Saitek PC Auto Chessboard	Jun 11, 2016
Saitek President	Jun 11, 2016
Shredder	Jan 21, 2018
SOS	Apr 5, 2017
SSDF	Feb 25, 2018
Stefan Meyer-Kahlen	Jun 19, 2017
Steve Lopez	Dec 4, 2016
Sven Reichard	Dec 28, 2016
Syzygy Bases	Apr 19, 2018
TASC SmartBoard	Feb 25, 2018
TCEC Season 11	Apr 18, 2018
The King	Jan 21, 2018
Thompson's Databases	Dec 24, 2014
Tony Hedlund	Jun 19, 2017
UCI	Mar 4, 2018
USB Chess Board	Apr 21, 2015
Vasik Rajlich	Sep 23, 2017
Wb2UCI	Feb 1, 2018
WCCC 1992	Feb 26, 2018
WCCC 1995	Jul 12, 2017
WCCC 1999	Jul 13, 2017
WCCC 2002	Nov 24, 2017
WCCC 2003	Apr 2, 2017
WCCC 2004	Jan 28, 2018
WCCC 2005	Dec 27, 2016
Windows	Nov 2, 2017
WMCCC 1995	Jan 3, 2018
WMCCC 1996	Sep 15, 2016
WMCCC 1997	Apr 4, 2017
WMCCC 2000	Feb 27, 2018
World Computer Chess Championship	Mar 6, 2018
Yace	Dec 31, 2017
Zappa	Oct 24, 2017
Zappa versus Rybka 2007	Nov 25, 2017
Zarkov	Feb 26, 2018

Up one Level

Horizon Node

GerdIsenberg — Tue, 13 Sep 2016 10:01:47 GMT

Home * Search * Node * Horizon Node

Horizon nodes are nodes at depth zero, where a quiescence search is performed. The definition is taken from the papers of Ernst A. Heinz ^[1] depth == 0 nodes ^[2]. If the horizon node is an expected Cut-Node, confirmed by the evaluated standing pat score already greater or equal than beta, the horizon node is a leaf with the lower bound score of beta (fail-hard) or the stand pat score (fail-soft). Otherwise, winning captures (or checks) may either cause a beta-cutoff or raise alpha with an exact score at PV-Nodes. At expected All-Nodes with evaluated score (far) below alpha, if no tactical move is available, or due to Delta Pruning good enough to raise alpha, those leaves return alpha (fail-hard) as an upper bound. This may also appear, if this horizon node was not a leaf, since some captures were not pruned, but tried without raising alpha.

Horizon Observatory

Horizon Observatory (left) and horizontal Sundial with Obelisk (right), Hoheward Spoil tip, The Industrial Heritage Trail ^[3]

External Links

Karl Jenkins - In These Stones Horizons Sing (4th movement), YouTube Video
Commissioned for the opening of Wales Millennium Centre, first performed at its opening on November 29, 2004

References

^ Ernst A. Heinz (1998). Extended futility pruning. ICCA Journal, Vol. 21, No 2, ps
^ Re: simple node definitions question by Robert Hyatt, CCC, September 13, 2004
^ 360–degree Panorama Photo by Panofreak, April 12, 2009, Hoheward Spoil tip in Herten, North Rhine-Westphalia, Germany, The Industrial Heritage Trail , view over the Ruhr area. The observatory consists of a circular, flat surface of 88 m diameter, and a center forum lowered by 1.50 m with 35 m diameter with two arcs spanning meridian and celestial equator. The horizon observatory is a modern version of prehistoric stone circles and monuments such as Stonehenge. If the observer is located exactly in the lowered center, the plateau of the tip spreads in all directions like an artificial horizon, and with the help of bearing points the sunrise and sunset at summer solstice, winter solstice or equinox can be observed, by means of further bearing points also moon solstices and the precession of Earth's axis based on bearings of fixed stars. The arcs divide the celestial sphere in eastern and western half as well as in northern and southern hemisphere and therefore serve as a solar calendar at day, and at night, with the help of a self-luminous scale as a guide of the night sky, Halden im Ruhrgebiet (German)

What links here?

Page	Date Edited
Check	Feb 1, 2018
Depth	Feb 25, 2018
Double Attack	Oct 22, 2014
Frontier Nodes	Dec 29, 2013
Gazebo	May 21, 2017
Gibbon	Dec 23, 2014
Horizon	Mar 17, 2013
Horizon Effect	Sep 10, 2017
Horizon Node	Sep 13, 2016
Interior Node	Aug 6, 2012
Leaf Node	Mar 4, 2017
Mate Threat Extensions	Apr 14, 2012
Murka	Nov 11, 2016
NegaScout	Jul 6, 2016
Node	Jul 20, 2015
Oracle	Sep 4, 2016
Ostrich	Dec 28, 2017
Ply	Jan 27, 2014
Quiescence Search	Aug 19, 2017
Quiescent Node	Feb 10, 2017
Razoring	Oct 5, 2015
Sacrifice	Aug 10, 2017
Stalemate	Feb 21, 2018
Tactics	Jan 12, 2018
Undermining	Jun 10, 2012

Up one Level

Iterative Search

GerdIsenberg — Thu, 20 Oct 2016 19:29:51 GMT

Home * Search * Iterative Search

		The more common search structure is the recursive depth-first search, as used in the Negamax algorithm example. The function calls itself with a decremented depth parameter until depth reaches zero. Opposed to that the Iterative Search always remains on the same layer on the call stack.
Spaghetti Code ^[1]

Introduction

Knuth and Moore already introduced an iterative solution of Alpha-Beta in 1975 ^[2]:

It is interesting to convert this recursive procedure to an iterative (non-recursive) form by a sequence of mechanical transformations, and to apply simple optimizations which preserve program correctness. The resulting procedure is surprisingly simple, but not as easy to prove correct as the recursive form.

Considerations

Generally every Recursive Function can also be converted into an Iterative Search by means of replacing the function calls by jumps (goto, break, continue) within the function itself ^[3]. The result is usually more efficient as the calling of a function is slower than just jumps within the function. The main downside however is the increased complexity and decreased readability ^[4].

In the Recursive Search the function can store local values, this doesn't work for the Iterative Structure, as all plies are using the same function. As a result a separate structure has to be maintained with all the relevant information for each ply. Harm Geert Muller (2008) ^[5] also pointed out that this gives more control to the programmer as to where the stack data maps in cache, allowing for more efficient implementations. Furthermore Onno Garms (2010) ^[6] said that the Iterative Search favors Profiling, as avoids all the cycles in the call tree.

Parallel Search

Especially for the Parallel Search Algorithm Dynamic Tree Splitting having an Iterative Search Structure is essential. It relies on threads frequently changing ownership of certain nodes, which requires full control over search stacks ^[7]. Furthermore it gives more flexibility in the selection of Split Points as the information on nodes in the current search branch is freely available.

Implementations

Goto

Onno Garms suggests the use of goto with a switch at the bottom to jump to the label specified in ret_addr as applied in his engine Onno:

namespace Label
{
  enum _ {after_scout, after_research, ...};
}
 
class Node
{
  int alpha, beta;
  Move move;
  MoveList moves;
  int value;
  Label::_ ret_addr;
};
 
search ()
{
  Node* node = &d_nodes[0];
  Node* child = node+1;
 
recurse:
  node->moves.init();
  while ((node->move = node->moves.next()))
  {
    child->alpha = ...
    child->beta = ...
    child->ret_addr = Label::after_scout;
    ++node;
    ++child;
    goto recurse;
    // when we return here, node and child have their original values
    // and child is evaluated
after_scout:
    if (child->value < -node->alpha)
    {
      child->alpha = ...
      child->beta = ...
      child->ret_addr = Label::after_research;
      ++node
      ++child;
      goto recurse;
    after_research:
      ...
    }
    if (cutoff)
    {
      node->value = ...
      goto node_done;
    }
  }
node_done:
  --node;
  --child;
  switch (child->ret_addr)
  {
    case Label::after_research:
      goto after_research;
    ...
  }
}

Edmund Moshammer suggested to use a branch table, which at the beginning gets filled with addresses of all return points. The difference to the code shown by Onno Garms is that this would avoid the additional indirection of the switch statement in the end.

Switch

Teemu Pudas suggests a way how to use switch statements hiding behinds macros that emulate the typical function calls ^[8]:

enum { RETURN, NEW_NODE };
 
#define be_recursive() \
   switch (state) { \
   case NEW_NODE
#define end_recursion() \
   default:assert(false); return best; }
 
#define return(foo) return best = foo, RETURN
#define recurse() return(best), NEW_NODE
 
#define search(depth,alpha,beta) do { \
   next->init(NEW_NODE,depth,alpha,beta); \
   state = __LINE__; \
   recurse(); \
   case __LINE__:; } while (0)
 
 
inline int Node::do_search() {
 
// any variable not declared inside this function is a member of Node
 
Node *const next = this + 1;
 
be_recursive(): // Please.
 
   gen_moves(list);
   if (list.empty()) return(in_check ? MATE_IN_ONE : DRAW);
 
   while (move = list.next()) {
      make(move);
      search(depth-1,-beta,-alpha);
      unmake();
      if (ret_val > best) {
         best = ret_val;
         if (best >= beta) return(best);
      }
   }
   return(best);
 
end_recursion();
}
 
int drive_search(int depth, int alpha, int beta) { // called from root_search()
   Node stack[MaxPly];
   Node *node = &stack[1]; // stack[0] would be root
   node->init(NEW_NODE,depth,alpha,beta);
   while (true) {
      switch (node->do_search()) {
      case RETURN:
         node--;
         node->ret_val = -node[1].best;
         if (node == stack) return node->ret_val;
         break;
      case NEW_NODE:
         node++;
      }
   }
}

Zach Wegner, the author of ZCT uses a large switch branch spanning across the search function with labels for every return point ^[9].

Forums Posts

2005 ...

recusive null move in iterative search by Daniel Shawul, Winboard Forum, March 25, 2005 » Null Move Pruning
Iterative alpha-beta search? by Andrew Wagner, CCC, January 11, 2006
Iterative DTS by Fritz Reul, CCC, July 02, 2007
Interesting Scorpio design by Kerwin, Winboard Forum, November 05, 2008
Iterative version of Alpha-beta instead recursive by Samuele Giraudo, CCC, May 02, 2009

2010 ...

DTS Structure by Edmund Moshammer, CCC, May 28, 2010
True iterative search... by Jens Bæk Nielsen, CCC, November 27, 2012
Re: goto thread (split) by Steven Edwards, CCC, August 01, 2013 » Symbolic ^[10]
Non recursive perft() by Steven Edwards, CCC, August 24, 2014 » Perft

2015 ...

Parallel iterative search function by Fabio Gobbato, CCC, March 05, 2015 » Parallel Search

References

^ Irmgard Potthoff - Keine Schonkost, 2010, Überschriften aus Tageszeitungen, Teller, Messer, Gabel, Tisch (headlines from daily newspapers, plate, knife, fork, table), Flottmann 30 hoch - 30 years anniversary exhibition, Flottmann-Hallen in Herne, North Rhine-Westphalia, Germany, part of The Industrial Heritage Trail of the Ruhr area, Photo by Gerd Isenberg, September 18, 2016
^ Donald Knuth, Ronald W. Moore (1975). An analysis of alpha-beta pruning. Artificial Intelligence, 6:293–326
^ comp.lang.c FAQ list · Question 17.10
^ Spaghetti code from Wikipedia
^ Re: Interesting Scorpio design by H.G. Muller, Winboard Forum, November 05, 2008
^ Re: DTS Structure by Onno Garms, CCC, May 28, 2010
^ See remark on Recursion by Jean-Christophe Weill on recursive versus iterative implementation of ABDADA
^ Re: Interesting Scorpio design by Teemu Pudas, Winboard Forum, November 05, 2008
^ Re: DTS Structure by Zach Wegner, CCC, May 29, 2010
^ Considered harmful from Wikipedia

What links here?

Page	Date Edited
ABDADA	Aug 30, 2017
Algorithms	May 5, 2017
Alpha-Beta	Jan 28, 2018
Backtracking	Dec 16, 2017
Brute Force (Program)	Sep 7, 2017
Brutus	Dec 24, 2016
C	Feb 19, 2018
Chess 0.5	Nov 20, 2016
CookieCat	Nov 15, 2016
Dabbaba	Oct 21, 2014
Daniel Shawul	Jan 28, 2018
Deep Sjeng	Jan 7, 2016
Donald Knuth	Aug 29, 2016
Dynamic Tree Splitting	Apr 10, 2017
Edmund Moshammer	Sep 23, 2017
Fabio Gobbato	Mar 6, 2015
FPGA	Jul 9, 2016
FUSCsharp	Jun 7, 2013
Iteration	May 5, 2017
Iterative Search	Oct 20, 2016
Jens Bæk Nielsen	Mar 3, 2015
Johannes Buchner	May 26, 2013
Loop (Program)	Mar 14, 2017
Mate-in-two	Oct 14, 2016
Mini Chess	Jun 7, 2013
Negamax	Sep 11, 2015
Null Move Pruning	Dec 2, 2017
Onno	Jul 19, 2013
Parallel Search	Dec 30, 2017
Perft	Sep 26, 2017
Recursion	Nov 18, 2017
Scorpio	Mar 28, 2018
Search	Feb 1, 2018
SnailChess	Nov 26, 2014
Stack	Nov 18, 2016
Steven Edwards	Aug 26, 2017
Symbolic	May 8, 2017
Zach Wegner	Jan 7, 2016

Up one level

Linux

GerdIsenberg — Sun, 21 Jan 2018 17:59:29 GMT

Home * Software * Linux

		Linux, a Unix compatible operating system written by Linus Torvalds ^[1] and contributors. It has gained widespread use in most every aspect of computing technology. Linux's support for consumer grade chess engines and GUIs is not great, but is improving. Once, XBoard with GNU Chess was the only program, but now the commercial Shredder, and the free PyChess, Scid vs. PC, Cute Chess and Arena have polished interfaces and are easy to use. The powerful and fast database program, SCID (and it's many derivatives), make Linux a valid choice for chess professionals preparing for tournament matches.
The Linuxhotel ^[2]

Chess GUIs

Arena
ChessX
Cute Chess
EBoard
glChess
GNOME Chess
PyChess - Versatile chess program.
Scid vs. PC - Polished, user-friendly fork of SCID.
Shredder - Polished commercial product, with a 30 day trial.
XBoard

Chess Engines

XBoard engines

XBoard Engines supporting the XBoard protocol with the tag "xboardengines"

1. AdaChess
2. AICE
3. Alice
4. Amundsen
5. Amy
6. Arasan
7. BBChess (SI)
8. Belofte
9. Beowulf
10. Betsabe
11. Blikskottel
12. Brainless
13. Butcher
14. Buzz
15. Cassandre
16. Cheese
17. Chenard
18. Chesley
19. Chess for Android
20. chess4j
21. Clarabit
22. Crafty
23. CrazyWa
24. Cupcake
25. DanaSah
26. Deep Blue
27. DeepBrutePos
28. Djinn
29. Dorpsgek
30. Dragon FR
31. Dreamer
32. E.T.Chess
33. Enigma
34. Exacto
35. EXchess
36. Faile
37. Fairy-Max
38. Fizbo
39. Fortress (Engine)
40. Frenzee
41. Gaia
42. Galjoen
43. Gaviota
44. Genesis IL
45. Ghost
46. GiuChess
47. Gk
48. GNU Chess
49. Gothmog
50. Gullydeckel
51. Hermann
52. Hossa
53. Jabba
54. Jazz
55. Jellyfish
56. JikChess
57. Joker IT
58. KingSlayer
59. KnightX
60. Kurt
61. Little Wing
62. Marvin
63. MatMoi
64. MSCP
65. Murka
66. Natwarlal
67. Nemorino
68. NG-play
69. NoonianChess
70. Obender
71. Octochess
72. OliThink
73. Parrot
74. Patzer
75. Phalanx
76. Plisk
77. PostModernist
78. Prophet
79. Pulsar
80. Purple Haze
81. RattateChess
82. Rookie
83. Ruffian
84. Scidlet
85. Scorpio
86. Searcher
87. Sjaak (Glebbeek)
88. Sjeng
89. Sloppy
90. Small Potato
91. Sunsetter
92. The Crazy Bishop
93. Typhoon
94. Vice
95. Warrior
96. Woodpecker
97. WyldChess
98. Xadreco
99. Xpdnt
100. Yace

Linux compatible Engines

Linux compatible UCI Engines supporting the UCI protocol with the tag "linuxengines"

1. Arasan
2. Atlas (ESP)
3. Belofte
4. BikJump
5. Cassandre
6. Cheese
7. Cheng
8. Cinnamon
9. Critter
10. CT800
11. DayDreamer
12. Demolito
13. DiscoCheck
14. Embla
15. Fruit
16. Fruit Reloaded
17. Gaia
18. Gaviota
19. Glaurung
20. GullChess
21. Hakkapeliitta
22. Ifrit
23. Ippolit
24. Jabba
25. Jellyfish
26. JFresh
27. Kholin
28. Komodo
29. Marvin
30. Matheus
31. Maverick
32. MinkoChess
33. Pawny
34. Pedone
35. Plisk
36. Protector
37. RedQueen
38. Robocide
39. Rocinante
40. Rodent
41. Ruffian
42. RuyDos
43. Senpai
44. Shredder
45. Simplex
46. Sloppy
47. Spark
48. Spike
49. Stockfish
50. Superpawn
51. Teki
52. Texel
53. Tunguska
54. Winter
55. WyldChess
56. Xiphos
57. Zappa

User Interfaces

Development

OS Internals

Linux kernel from Wikipedia
The Linux Kernel by David A Rusling
Linux Activations by Vincent Danjean
A NUMA API for Linux (pdf, April 2015) » NUMA

IDE

C/C++

Libs

C standard library
GNU C Library from Wikipedia
GNU C Library - GNU Project - Free Software Foundation
Native POSIX Thread Library from Wikipedia
Qt (software) from Wikipedia
Boost (C++ libraries) from Wikipedia
Marcel a two-level scheduling thread library by Vincent Danjean

Compiler

Calling Conventions

Agner Fog describes x86 and x86-64 calling conventions for different C++ compilers and operating systems, covering 32-bit and 64-bit Linux ^[3] :

The document contains details about data representation, function calling conventions, register usage conventions, name mangling schemes, etc. for many different C++ compilers and operating systems. Discusses compatibilities and incompatibilities between different C++ compilers. Includes information that is not covered by the official Application Binary Interface standards (ABI's). The information provided here is based on my own research and therefore descriptive rather than normative. Intended as a source of reference for programmers who want to make function libraries compatible with multiple compilers or operating systems and for makers of compilers and other development tools who want their tools to be compatible with existing tools.

Other Languages

Publications

1999

Vincent Danjean (1999). Extending the Linux kernel with Activations for Better Support of Multithreaded Programs and Integration in PM2. Master thesis, Magistère d'informatique et modélisation (MIM), ENS Lyon, Sep. 1999, zipped ps

2000 ...

Vincent Danjean, Raymond Namyst, Robert Russell (2000). Integrating Kernel Activations in a Multithreaded Runtime System on Linux. Proc. 4th Workshop on Runtime Systems for Parallel Programming (RTSPP~'00), zipped ps
Vincent Danjean, Raymond Namyst, Robert Russell (2000). Linux Kernel Activations to Support Multithreading. Proc. 18th IASTED International Conference on Applied Informatics, zipped ps
Peter Jay Salzman, Ori Pomerantz (2001). The Linux Kernel Module Programming Guide.
Andi Kleen (2004). An NUMA API for Linux. SUSE Labs, pdf » NUMA

2010 ...

Forum Posts

2000 ...

Linux by Frank Phillips, CCC, May 12, 2001
Using 2 machines for matches (Linux) by Jon Dart, CCC, June 24, 2001 » XBoard
What is the future for Linux? by Leonid, CCC, October 03, 2002
Linux SMP by Russell Reagan, CCC, August 31, 2003 » SMP
Porting an engine to Linux by Josué Forte, Winboard Forum, September 18, 2003
chess GUI under Linux by Vasik Rajlich, CCC, March 23, 2004 » GUI

2005 ...

64-bit development in Linux by Gregory Strong, CCC, February 08, 2009

2010 ...

My experience with Linux/GCC by Richard Vida, CCC, March 23, 2011
Switching from Ubuntu by Steven Edwards, CCC, August 15, 2012
Debian 7 by Steven Edwards, CCC, May 25, 2013
Shogi in Unix/Linux? by Joshua Pettus, Winboard Forum, October 19, 2013 » Shogi
To GUI developers and Linux engine packagers by H.G.Muller, CCC, September 12, 2014 » GUI

2015 ...

Test epd for Linux ? by Jean Arthuin, CCC, March 25, 2016 » EPD, STS, XBoard
Linux Chess GUI that's good for engine matches/tournaments by Shawn Chidester, CCC, June 16, 2016 » GUI
Crashing engines (Linux) by Harm Geert Muller, CCC, September 18, 2016 » Process, XBoard
Arena for Linux by Jesse Gersenson, CCC, November 15, 2016 » Arena
What Linux compatible Numa aware engines are available? by Dann Corbit, CCC, March 29, 2017 » NUMA
For how many of these are there functional Linux versions? by Dann Corbit, CCC, October 07, 2017
Engines for testing (Linux, fast time control) by Jon Dart, CCC, November 18, 2017 » Engine Testing

Further Links

Distribution

Chess GUIs

Chess Databases

Scid vs. PC Currently without support for the latest Scid database format.
ChessX Gorgeous, but feature poor, QT based utility.
Scidb Still in development, but promises ChessBase support (read-only)

References

^ Linus' blog
^ Villa Vogelsang at the banks of river Ruhr, Essen Horst, Germany, domiciling the Linuxhotel GmbH, offering not only accommodation, but courses around Linux, applications, development, open-source, operating system, and web topics - part of The Industrial Heritage Trail of the Ruhr area. Photo by Gerd Isenberg, June 23, 2015
^ Calling conventions for different C++ compilers and operating systems (pdf) by Agner Fog

What links here?

Page	Date Edited
Aart Bik	Mar 1, 2018
AICE	Nov 29, 2017
Alfil	Sep 3, 2015
Alice	May 20, 2015
Android	Jan 9, 2018
Arasan	Apr 8, 2018
Arena	Mar 16, 2018
Ares US	Sep 20, 2016
asmFish	Feb 14, 2018
Atlas (ESP)	Jan 28, 2018
Bagatur	Sep 10, 2016
Basil Falcinelli	Jun 23, 2017
BBChess (SI)	Jan 12, 2015
Betsabe	Jul 23, 2017
BikJump	Aug 11, 2014
BitScan	Sep 10, 2017
Blikskottel	Feb 15, 2014
BootChess	May 16, 2017
Butcher	Mar 12, 2013
C	Feb 19, 2018
Cheese	Feb 17, 2018
Chenard	Sep 5, 2015
Cheng	Jul 30, 2017
ChessV	Jan 21, 2018
ChessX	Feb 26, 2015
Cinnamon	Sep 23, 2017
Clarabit	Nov 3, 2011
CLI	Jan 20, 2018
Commodore 64	Oct 27, 2016
Crafty	Jan 28, 2018
Critter	Jan 25, 2014
CT800	Feb 21, 2018
Cute Chess	Jul 20, 2017
DanaSah	Oct 9, 2017
Daniel Walker	Sep 28, 2015
DayDreamer	Aug 22, 2016
Delphi	Dec 16, 2016
Demolito	Mar 1, 2018
DiscoCheck	Jun 23, 2017
Djinn	Feb 8, 2016
Dreamer	Aug 5, 2015
Embla	Dec 3, 2017
Engine Testing	Feb 1, 2018
Extended Position Description	Dec 2, 2017
Fencer	Jan 20, 2013
Floyd	Sep 11, 2016
Flux	Jan 12, 2016
Frank Berger	Jan 16, 2017
Fritz	Feb 26, 2018
Fruit Reloaded	Dec 8, 2017
GAFS	Aug 14, 2016
Gaia	Nov 3, 2015
Gaviota	Jan 21, 2018
Gavon	Apr 30, 2018
Ghost	Feb 2, 2018
Gijsbert Wiesenekker	Jan 17, 2018
Glaurung	Mar 14, 2017
glChess	Aug 18, 2017
Glen Pepicelli	Aug 26, 2012
GNOME Chess	Aug 18, 2017
Graphic and Widgets to include	Apr 15, 2017
Gregory Strong	Apr 24, 2017
Gromit	Apr 5, 2017
GUI	Mar 16, 2018
GullChess	Jun 27, 2017
Gullydeckel	Oct 28, 2015
Gunda-1	Jan 8, 2016
Harun Taner	May 17, 2015
Homer	Dec 23, 2013
IBM PC	Dec 9, 2016
Ifrit	Feb 7, 2016
InBetween	Jan 21, 2018
Intel	Aug 29, 2015
Jabba	Sep 10, 2016
Java	Feb 25, 2018
Jazz	Oct 4, 2017
Jellyfish	Apr 26, 2016
Jerry	Mar 28, 2016
John Roland Penner	Mar 18, 2016
Joker IT	Sep 16, 2017
Jon Dart	Dec 17, 2017
Jonny	Nov 4, 2017
Jose	Feb 26, 2015
Joshua Shriver	Nov 24, 2017
Kiwi	Sep 2, 2016
KnightX	Jan 28, 2013
Komodo	Mar 6, 2018
Kurt Utzinger	Dec 30, 2017
Leonid Liberman	May 23, 2015
Linux	Jan 21, 2018
Linux Engines	Nov 4, 2010
Lomonosov Supercomputer	May 19, 2016
MadChess	Jul 4, 2017
Marco Costalba	Feb 28, 2018
Mark Watson	Apr 14, 2013
MatMoi	Jan 13, 2014
Memory	Dec 8, 2017
Michal Rudolf	May 30, 2014
MinkoChess	Sep 5, 2013
Naum	Nov 23, 2017
Norbert Raimund Leisner	Jul 28, 2016
NUMA	Mar 29, 2017
Octochess	Aug 15, 2017
OliThink	May 19, 2017
Onno	Jul 19, 2013
pcDuino	Sep 10, 2014
Pedone	Jan 16, 2018
Pedro Castro	Apr 19, 2016
Peter Garscha	Dec 10, 2017
Phalanx	May 2, 2016
Plisk	Dec 31, 2014
Point Value by Regression Analysis	Aug 26, 2017
PolyGlot	Jan 17, 2018
PostModernist	Jan 7, 2016
PowerPC	Oct 6, 2017
Process	Jul 31, 2017
Protector	Oct 12, 2017
Pulsar	May 4, 2017
Pulse	Aug 14, 2017
PyChess	Dec 28, 2017
Raspberry Pi	Jun 7, 2017
RedQueen	Nov 13, 2017
Richard P. Cochran	Mar 28, 2015
Richard Vida	Aug 11, 2013
Rinko	Feb 27, 2014
Robert Ancell	Aug 18, 2017
Rocinante	Feb 19, 2018
Ronald de Man	Nov 20, 2017
Scid vs. PC	Jan 21, 2018
Scorpio	Mar 28, 2018
Senpai	Nov 10, 2017
Shared Hash Table	Sep 11, 2017
Shared Memory to include	Nov 29, 2017
Shogi	Feb 19, 2018
Shredder	Jan 21, 2018
SIMD and SWAR Techniques	Jun 27, 2017
Sloppy	Sep 17, 2016
SMP	Dec 26, 2017
Software	Jul 28, 2017
Spark	Oct 19, 2017
Sun	Jun 7, 2016
Superpawn	Mar 9, 2015
Tapered Eval	Jan 9, 2018
Techno Chess	Jan 8, 2016
Thomas Dybdahl Ahle	Aug 26, 2017
Tunguska	Sep 16, 2017
UCI	Mar 4, 2018
UCI Engines	Dec 2, 2016
UCI2WB	Jan 21, 2018
UDOO	Oct 27, 2017
Unix	Jun 28, 2015
Vincent Danjean	Nov 18, 2012
Vlad Stamate	Dec 31, 2014
Windows	Nov 2, 2017
x86	Jan 4, 2018
x86-64	Mar 6, 2018
Xadreco	Jul 23, 2017
XBoard	Jan 21, 2018
Xiphos	Apr 22, 2018
Zappa	Oct 24, 2017
Zzzzzz	May 14, 2016

Up one Level

Loop (Program)

GerdIsenberg — Tue, 14 Mar 2017 15:01:56 GMT

Home * Engines * Loop

		Loop, a chess program by Fritz Reul with different board representations for 32-bit and 64-bit platforms as subject of Reul's Ph.D. thesis New Architectures in Computer Chess ^[1] . Despite different board representation, both Loop versions presumably share same search and evaluation with similar features and weights.
Tiger and Turtle - illuminated looping ^[2]

32-bit Loop

64-bit Loop

Evaluation

Preliminary Considerations

Fruit Evaluation Overlap

32-bit Loop

The 32-bit program, based on Reul's former program List, relies on a 15x12 board representation in conjunction with disjoint piece-lists with adequate move generation of blocker loops. It participated as Loop Leiden at the DOCCC 2006, becoming strong runner up behind Rybka. A specially adapted version called Loop Express became the engine of Wii Chess for the Nintendo Wii console in 2008 ^[3] . The non-bitboard data-structure of Loop was also applied in Chrilly Donninger's chess machine Hydra ^[4] .

Reul in his thesis ^[5] :

This computerchess architecture was first implemented in the quite successful computerchess engine Loop Leiden 2006. The computerchess architecture was later implemented partially in Hydra and completely in Wii Chess by Nintendo (see Section 2.1). The high performance was just as important for these projects as the simplicity and ease of implementation in the following two environments: (1) the environment of a sophisticated computer-chess machine (Hydra) and (2) the environment of a commercial games console with the highest quality and security standards.

64-bit Loop

The bitboard based Loop applies Magic Bitboards for sliding piece attack generation. Further, iterative alpha-beta bounded static exchange evaluation was applied to Loop Amsterdam ^[6] , also performing a parallel search for a quad-core processor, which played a strong WCCC 2007 in Amsterdam, and became Third, behind the later disqualified Rybka, and Zappa ^[7] .

Fritz Reul on an essential reason of Loop's success in Amsterdam in his thesis ^[8] :

A complete computer-chess architecture based on hash functions and magic multiplications for the examination of bitboards is implemented in the computerchess engine Loop Amsterdam. This engine was able to reach the 3rd place at the 15th World Computer-Chess Championship, Amsterdam (NL) 2007. An essential reason for the success of this 64-bit computer-chess engine was the use of highly sophisticated perfect hash functions and magic multipliers for the computation of compound bit-patterns (bitboards) via perfect hashing.

Evaluation

Preliminary Considerations

Evaluation was only marginally covered in Reul's thesis. In Preliminary Considerations he mentioned discussions with Chrilly Donninger, Fabien Letouzey and Tord Romstad, and the exchange of source codes ^[9] :

This thesis also does not aim at the explicit consideration of known computer-chess architectures, such as Rotated Bitboards ^[10] ^[11] or the 0x88 representation ^[12]. Many a reference used in this thesis is not available in a scientifically elaborate form. This includes personal conversations with programmers ^[13], ^[14] ^[15] and the exchange of source codes as well as discussions via email. In this way the contents of this thesis can be regarded to be on a state-of the-art level of the research and development in the field of the computer-chess architectures.

Fruit Evaluation Overlap

During the ICGA Investigations concerning the Rybka Controversy and evaluation overlaps, 64-bit Loop was inspected by Mark Watkins who found congruence with the evaluation of Fruit 2.1 ^[16] . As confirmed by David Levy ^[17], the ICGA has received a complaint on Loop by Fruit author Fabien Letouzey and an investigation has been started about this case, as already mentioned by Watkins in August 2011 ^[18] .

Complaints

ICGA President David Levy, May 09, 2014 ^[19]

The ICGA has received formal complaints against the Chess programs LOOP and THINKER, both of which have participated in the World Computer Chess Championship. LOOP was entered by Fritz Reul into the 2007 WCCC in Amsterdam. THINKER was entered into the 2010 WCCC in Kanazawa.
...
Here we present extracts from the first section of each of Mark Watkins reports.

Loop “The version examined here is Loop 2007 (64-bit), which was released at approximately the same time as the WCCC. There is notable similarity to Fruit in the evaluation function (other components were not examined).”
...
Based on the above mentioned reports by Mark Watkins the ICGA is convinced that, at the very least, both Fritz Reul and Kerwin Medina have a case to answer. Depending on how Reul and/or Medina respond to these allegations the ICGA might decide to conduct further investigations and/or take some form of strong sanctioning action against the programmers. However, the ICGA does not intend to proceed further along the route to strong sanctions for the time being, in order to give these programmers more time in which to make contact with the ICGA President and present their defence to the allegations. If either or both of these programmers fail to do so by December 31st 2014, or refuses to do so, the ICGA will disqualify them from all their results in ICGA events. In the meantime the ICGA has decided to suspend both Fritz Reul and Kerwin Medina from participation in all ICGA events until such time as they have made contact and offered a defence.

Publications

Fritz Reul (2009). New Architectures in Computer Chess. Ph.D. Thesis
Fritz Reul (2010). Static Exchange Evaluation with αβ-Approach. ICGA Journal, Vol. 33, No. 1

Forum Posts

2005 ...

Loop List available soon by Fritz Reul, CCC, October 11, 2005
Re: Loop List commercially available soon by Günther Simon, CCC, October 11, 2005
Loop 13.6 soon available by Gerhard Sonnabend, CCC, April 20, 2007
doing undoing by Fritz Reul, CCC, May 14, 2007
Iterative DTS by Fritz Reul, CCC, July 02, 2007
Re: Bob Hyatt says that... by Mike Scheidl, CCC, August 29, 2008
Re: Bob Hyatt says that... by Uri Blass, CCC, August 30, 2008

2010 ...

Loop 2007 / Fruit 2.1 by BB+, OpenChess Forum, April 18, 2011 » Fruit
Loop as a Fruit clone by Rebel, Rybka Forum, September 20, 2013
Complaints against the Chess programs LOOP and THINKER by Harvey Williamson, Hiarcs Forum, May 12, 2014
Complaints against the Chess programs LOOP and THINKER by Harvey Williamson, CCC, May 14, 2014

2015 ...

Re: FIDE Rules on ICGA - Rybka controversy by BB+, OpenChess Forum, May 08, 2015

External Links

Chess Engine

List's ICGA Tournaments (covers Loop)
Wii Chess from Wikipedia
ICGA/Rybka controversy: Feedback - Allegations against another Chess Engine – The LOOP Program by David Levy, ChessBase News, February 17, 2012
Allegations against two more Chess Engines – The LOOP Program by David Levy, ICGA president, May 22, 2012 » Thinker
Complaints against the Chess programs LOOP and THINKER by David Levy, ICGA President, May 9, 2014

Misc

References

^ Fritz Reul (2009). New Architectures in Computer Chess. Ph.D. Thesis
^ Tiger and Turtle – Magic Mountain is a monument in the Angerpark in Duisburg, Germany. Here you see its illuminated looping at night, Image by Kleunam, November 18, 2011, CC BY-SA 3.0, Category:Tiger and Turtle – Magic Mountain, Wikimedia Commons, The Industrial Heritage Trail
^ Fritz Reul (2009). New Architectures in Computer Chess, Ph.D. Thesis, 2.2.2 Nintendo Wii Chess, pp. 11
^ Fritz Reul (2009). New Architectures in Computer Chess, Ph.D. Thesis, 2.2.1 The Chess Machine Hydra, pp. 11
^ Fritz Reul (2009). New Architectures in Computer Chess, Ph.D. Thesis, 5.1.1 Non-Bitboard Architectures, pp. 96
^ Fritz Reul (2010). Static Exchange Evaluation with αβ-Approach. ICGA Journal, Vol. 33, No. 1
^ 15th World Computer Chess Championship - Amsterdam 2007 (ICGA Tournaments)
^ Fritz Reul (2009). New Architectures in Computer Chess, Ph.D. Thesis, 5.1.2 Magic Hash Functions for Bitboards, pp. 97
^ Fritz Reul (2009). New Architectures in Computer Chess, Ph.D. Thesis, 1.2 Preliminary Considerations, pp. 3-4
^ Stuart Cracraft (1984). Bitmap move generation in Chess. ICCA Journal, Vol. 7, No. 3
^ Robert Hyatt (1999). Rotated Bitmaps, a New Twist on an Old Idea. ICCA Journal, Vol. 22, No. 4
^ 0x88 Move Generation by Bruce Moreland
^ Chrilly Donninger (2006). Discussion with Dr. Christian Donninger.
^ Fabien Letouzey (2006). Personal discussion with Fabien Letouzey.
^ Tord Romstad (2007). Discussion with Tord Romstad.
^ Loop 2007 / Fruit 2.1 by BB+, OpenChess Forum, April 18, 2011
^ ICGA/Rybka controversy: Feedback - Allegations against another Chess Engine – The LOOP Program by David Levy, ChessBase News, February 17, 2012
^ Re: Loop 2007 / Fruit 2.1 by BB+, OpenChess Forum, August 22, 2011
^ Complaints against the Chess programs LOOP and THINKER by David Levy, ICGA President, May 9, 2014

What links here?

Page	Date Edited
CCT9	Aug 25, 2013
Chess960CWC 2006	Sep 25, 2014
Clemens Keck	Oct 15, 2017
Coiled	Mar 12, 2017
DOCCC 2006	Aug 27, 2016
Eigenmann Endgame Test	Jun 1, 2017
Engines	Mar 10, 2018
Fritz Reul	Nov 28, 2016
Fruit	Sep 27, 2016
ICGA Investigations	May 8, 2015
List (Program)	Jan 7, 2016
Loop (Program)	Mar 14, 2017
Mark Watkins	Dec 6, 2017
Mathematician	Apr 9, 2018
Piece-Lists	Feb 13, 2017
Rybka Controversy	Jan 18, 2018
Thinker	Jan 7, 2016
Vadim Demichev	Jul 26, 2013
Vector Attacks	Dec 15, 2017
WCCC 2007	Jan 2, 2017
Wii Chess	Jun 3, 2016

Up one level

Move Generation

GerdIsenberg — Mon, 29 Jan 2018 08:17:10 GMT

Home * Board Representation * Move Generation

		Generation of moves is a basic part of a chess engine with many variations concerning a generator or an iterator to loop over moves inside the search routine. The implementation heavily depends on the board representation, and it can be generalized into two types, pseudo-legal and legal move generation.
Blast Generation ^[1]

Legality

Pseudo-legal

In Pseudo-legal move generation pieces obey their normal rules of movement, but they're not checked beforehand to see if they'll leave the king in check. It is left up to the move-making function to test the move, or it is even possible to let the king remain in check and only test for the capture of the king on the next move.

Legal

In Legal move generation, as the name implies, only legal moves are generated, which means extra time must be spent to make sure the king isn't going to be left or placed in check after each move. Pins are the main difficulty, particularly when en passant is involved.

Special Generators

Most programs use special move generators for the quiescence search, sometimes supplemented by one for getting out of check. These special cases can be made more efficient than generating and testing each possible move to fit specific criteria. For example, if the king is in check, the only possible legal moves are to capture the attacking piece, block the attacker if it is a "ray" piece, or move the king to safety. Special generators for the quiescence search might want to generate checks in addition to captures and promotions. They can use the fact that a knight or bishop must start off on the same color square as the opponent king if they are to attack it. And rooks can only generate at most 2 checking moves...to the squares with the rook's column and the king's row or the king's column and the rooks row.

Similar tricks can be used for generating possible moves out of check, which must be by the king, capturing the opponent's checking piece, or blocking its attack if it is a ray piece. When in double check, only king moves are permitted.

Chunk move generation

With move ordering in mind, chess programs, while traversing pieces and their move-target sets once, store and buffer generated moves inside one or two move lists (i.e. for tactical and quiet moves), which is convenient for book-keeping and assigning scores based on MVV-LVA, SEE, history, piece square table etc., to later perform a selection sort before actually making the move.

Staged move generation

Some programs do not generate all moves at once, but do it in several stages (i.e. hash move first, then captures, then killer moves, then all the rest in a chunk) on the premise that if one of the early moves causes a cutoff, then we may save on the effort of generating the rest of the moves ^[2].

Debugging

It is important to ensure that the move generator works properly. Although this could be tested by playing many games, a better approach is to write a Perft function. This function recursively generates moves for the current position and all children up to a certain depth, and by counting all the leaf nodes, it can be compared to a table of values to test its accuracy.

Publications

1950 ...

Dietrich Prinz (1952). Robot Chess. Research, Vol. 6, reprinted 1988 in Computer Chess Compendium

1970 ...

Alex Bell (1972). Games Playing with Computers. Allen & Unwin, ISBN-13: 978-0080212227
Gerard Zieliński (1976). Arrays for Programming Chess. Kybernetes, Vol. 5, No. 2
Ozalp Babaoglu (1977). Hardware implementation of the legal move generation and relative ordering functions for the game of chess. Master's thesis, University of California, Berkeley
Peter W. Frey (1977). An Introduction to Computer Chess. Chess Skill in Man and Machine pp. 54-81

1980 ...

Joe Condon, Ken Thompson (1982). Belle Chess Hardware, Advances in Computer Chess 3, Reprinted (1988) in Computer Chess Compendium
Greg Bakker, Jim Jonkman, Jonathan Schaeffer, Tom Schultz (1982). VLSI Implementation of a Chess Legal Move Generator. EE755S-1, University of Waterloo ^[3]
Jonathan Schaeffer, Patrick A.D. Powell, Jim Jonkman (1983). A VLSI legal move generator for the game of chess. in Randal Bryant (eds.) Third Caltech Conference on Very Large Scale Integration
Carl Ebeling, Andrew James Palay (1984). The Design and Implementation of a VLSI Chess Move Generator. Proceedings of the 11th Annual International Symposium on Computer Architecture. IEEE and ACM.
Stuart Cracraft (1984). Bitmap move generation in Chess. ICCA Journal, Vol. 7, No. 3
Burton Wendroff (1985). Attack Detection and Move Generation on the X-MP/48. ICCA Journal, Vol. 8, No. 2
Carl Ebeling (1986). All the Right Moves: A VLSI Architecture for Chess. Ph.D. thesis, Carnegie Mellon University, MIT Press, Cambridge, MA. ISBN 0-262-05035-8.
Feng-hsiung Hsu (1986). Two designs of functional units for VLSI based chess machines. Carnegie Mellon University, Computer Science Department. Paper 1566.
Feng-hsiung Hsu (1987). A Two-Million Moves/Sec CMOS Single-Chip Chess Move Generator. IEEE J. of Solid-state Circuits, Vol. 22, No. 5, pp. 841-846.

1990 ...

James Testa, Alvin M. Despain (1990). A CMOS VLSI chess microprocessor. University of California, Berkeley, IEEE Custom Integrated Circuit Conference
Chun Ye (1992). Experiments in Selective Search Extensions. MSc. thesis, Department of Computing Science, University of Alberta, pdf
Yi-Fan Ke, Tai-Ming Parng (1996). Parallel Move Generation System for Computer Chess. IEICE Transactions on Information and Systems, April, 1996, pp. 290-296
Ernst A. Heinz (1997). How DarkThought Plays Chess. ICCA Journal, Vol. 20, No. 3
Robert Hyatt (1999). Rotated Bitmaps, a New Twist on an Old Idea. ICCA Journal, Vol. 22, No. 4
Feng-hsiung Hsu (1999). IBM’s Deep Blue Chess Grandmaster Chips. pdf

2000 ...

Reijer Grimbergen, Hitoshi Matsubara (2001). Plausible Move Generation in Two-Player Complete Information Games Using Static Evaluation. Transactions of the Japanese Society for Artificial Intelligence, Vol.16, pp. 55-62. pdf
Marc Boulé (2002). An FPGA Move Generator for the Game of Chess. Masters thesis, McGill University, (Supervisor: Zeljko Zilic, Co-Supervisor: Monty Newborn), pdf
Marc Boulé, Zeljko Zilic (2002). An FPGA Move Generator for the Game of Chess. McGill University, pdf » FPGA
Marc Boulé, Zeljko Zilic (2002). An FPGA Move Generator for the Game of Chess. ICGA Journal, Vol. 25, No. 2, pdf
Reijer Grimbergen (2007). Using Bitboards for Move Generation in Shogi. ICGA Journal, Vol. 30, No. 1, pdf, was topic of the 11th Game Programming Workshop
Fritz Reul (2009). New Architectures in Computer Chess, Ph.D. Thesis, pdf

2010 ...

Adrien Couetoux, Olivier Teytaud, Hassen Doghmen (2012). Learning a Move-Generator for Upper Confidence Trees. ICS 2012, Hualien, Taiwan, December 2012 » Learning, UCT

Forum Posts

1990 ...

move generators in computer chess by Deniz Yuret, rgcc, October 11, 1994
Re: move generators in computer chess, Tricky bit tricks by Marcel van Kervinck, rgcc, October 20, 1994 » Traversing Subsets of a Set
bitboard move generation by Robert Hyatt, rgc, October 25, 1994
move generators in computer chess by Joël Rivat, rgc, October 26, 1994
bitboard move generator by Joël Rivat, rgc, November 13, 1994
Speed of Move Generator by Valavan Manohararajah, rgcc, August 15, 1995
Move generator design choices by Martin Borriss, rgcc, April 26, 1996
Sane numbers by Martin Borriss, rgcc, June 26, 1996
GNU move generation by Jan Willem de Kort, rgcc, March 18, 1998 » GNU Chess

2000 ...

Fast BB move generation by Bas Hamstra, CCC, May 08, 2000
move_generation + hash by Georg von Zimmermann, CCC, May 28, 2000
Pre-calculated move generation by Ujecrh, CCC, June 26, 2000
Move generation question for the big boys by Sune Fischer, CCC, September 15, 2001
Precomputed move information by Sune Fischer, CCC, July 02, 2002
Natural move generation with bitboards (was Re:significant math) by Alessandro Damiani, CCC, November 20, 2002
Strength question by Bruce Moreland, CCC, January 05, 2003
Which open source chess program has the fastest move generator? by Dennis Breuker, CCC, April 25, 2003
Improvements in BF makes my MoveGen suck =( by Albert Bertilsson, CCC, June 26, 2003 » Branching Factor
Speed improvement in split move generation by Federico Corigliano, CCC, August 16, 2003
Move Generation Speed by Dan Honeycutt, Winboard Forum, October 21, 2004

2005 ...

Is it time for another new move generator? by Michael Sherwin, CCC, November 11, 2007
Did someone mention the GNUChess move Generator? by Michael Sherwin, CCC, November 12, 2007 » GNU Chess
Move generator by kongsian, CCC, April 12, 2008
Bitboards / move generation on larger boards by Gregory Strong, CCC, January 09, 2009
Move generation: staged vs all-at-once by Steven Edwards, CCC, April 30, 2009
Re: Move generation: staged vs all-at-once by Lance Perkins, CCC, April 30, 2009

2010 ...

Assembly move generation in Freccia by Stefano Gemma, CCC, July 26, 2011

2012

move generation speed by Folkert van Heusden, Winboard Forum, January 03, 2012
Is there such a thing as branchless move generation? by John Hamlen, CCC, June 07, 2012 » DirGolem, GPU
hyper threading and move generation by Gabor Buella, CCC, August 01, 2012
What's the fastest move generator? by Marcel Fournier, CCC, August 29, 2012
Re: Question About CPP-C#, Performance, and Square Representation by Erik Madsen, CCC, October 03, 2012 » MadChess ^[4] ^[5]
Plausible move generator by Jorge Garcia, CCC, November 09, 2012
Diepeveen's move generator by Hrvoje Horvatic, CCC, November 18, 2012 » Table-driven Move Generation

2014

Just another movegen by Syed Fahad, CCC, November 14, 2014
How to call the Satana move generation by Stefano Gemma, CCC, November 17, 2014 » Satana
Black/White symmetry in move generation by Jeffery A Esposito, CCC, November 25, 2014 » Color Flipping
Symmetric move generation using bitboards by Lasse Hansen, CCC, December 20, 2014
Reverse move generation by Kostas Oreopoulos, December 30, 2014 » Retrograde Analysis

2015 ...

On bitboard legal move generation by Lasse Hansen, CCC, February 09, 2015
Questions about chess programming from a newbie by Matt Palmer, CCC, April 18, 2015
Caching generated moves list in recursive searches by Rein Halbersma, CCC, May 10, 2015

2016

speed up your engine part 4 by Laurie Tunnicliffe, CCC, August 03, 2016 » Staged move generation
Performance diff between legal / illegal move generator by Mahmoud Uthman, CCC, October 22, 2016

2017

Most efficient way to generate legal king moves? by notachessplayer, OpenChess Forum, February 04, 2017
Back to the basics, generating moves on gpu in parallel... by Srdja Matovic, CCC, March 05, 2017 » GPU
Fastest pawn quiet move generation I was able to come with by Daniel José Queraltó, CCC, June 10, 2017 » Duff's Device
History heuristic and quiet move generation by Daniel José Queraltó, CCC, July 16, 2017 » History Heuristic
Skipping duplicat moves by Harm Geert Muller, CCC, December 03, 2017

External Links

Chapter 3: Board Games - 3.1 CHESS from Alex Bell (1972). Games Playing with Computers. Allen & Unwin, ISBN-13: 978-0080212227
Description of 0x88 method from Bruce Moreland's Programming Topics
Move Table move generation from Bruce Moreland's Programming Topics
How Zarkov Plays Chess by John Stanback
Monsoon/Typhoon Homepage by Scott Gasch, covers 0x88 move generation
generate.c by Scott Gasch
Description of Rotated Bitboards by Robert Hyatt
Buzz - A Winboard Chess Playing Program by Pradu Kannan - Source of magic Move Generator
Chess Programming Part III: Move Generation by François-Dominic Laramée, gamedev.net, July 2000
Chess Move Generator - Computer Architecture and Languages Laboratory, University of Maribor
Engine - Hispanic Chess Engines | The move generator by Pedro Castro
Generator (computer programming) from Wikipedia

References

^ electric driven air compressor in the machine hall of Zollern II/IV Colliery, Dortmund Bövinghausen, Germany - part of The Industrial Heritage Trail, Photo by Gerd Isenberg, September 18, 2016
^ Move generation: staged vs all-at-once by Steven Edwards, CCC, April 30, 2009
^ 1983 | Waking up to change in Chris Redmond and Simon the Troll (1998). Water Under the Bridge. University of Waterloo » VLSI Move Generation
^ yield - MSDN C# Reference
^ Behind the scenes of the C# yield keyword | Struggles by Lars Corneliussen, June 9, 2008

What links here?

Page	Date Edited
0x88	Nov 28, 2016
10x12 Board	Feb 19, 2018
8x8 Board	Aug 29, 2017
Abyss	Aug 5, 2017
Advance	Jan 7, 2016
Alaric	Mar 4, 2014
Albert Bertilsson	Jun 6, 2017
Algebraic Chess Notation	Sep 25, 2017
AltiVec	Jun 7, 2016
Amoeba	Mar 19, 2018
Anechka	Mar 20, 2014
Ankan Banerjee	Aug 26, 2017
Arion	Nov 28, 2014
Atlas	Nov 5, 2017
Attack and Defend Maps	Nov 5, 2016
Bas Hamstra	Feb 4, 2018
Beaches	Jun 10, 2017
Bebe	Dec 23, 2017
BELCT 2001	Apr 4, 2017
Belle	Jan 18, 2018
Beowulf	May 5, 2017
Berkeley Chess Microprocessor	May 22, 2013
Betsabe	Jul 23, 2017
Bitboard Serialization	Dec 24, 2014
Bitboards	Nov 14, 2017
Bitfoot	Sep 8, 2015
BlackBishop	Nov 7, 2014
Board Representation	Dec 11, 2017
Bobby	Jan 7, 2016
BP	Jan 7, 2016
Branching Factor	Jun 28, 2017
Bruja	Feb 3, 2015
Brutus	Dec 24, 2016
CAPS	Dec 23, 2017
Capture (program)	Jan 8, 2016
Captures	Oct 1, 2017
Carballo	Oct 2, 2016
Check	Feb 1, 2018
Checkmate	Apr 13, 2018
Checks and Pinned Pieces (Bitboards)	Aug 14, 2013
Cheiron	Jan 7, 2016
Chenard	Sep 5, 2015
Cheng	Jul 30, 2017
CHEOPS	Apr 18, 2015
Cheops (Miller)	Jan 13, 2017
Chess 0.5	Nov 20, 2016
Chess Brain	Jun 25, 2017
chess4j	Jan 1, 2018
ChessBase (Database)	Feb 26, 2018
Chest	Mar 3, 2015
ChipTest	Jun 19, 2016
Coiled	Mar 12, 2017
Color Flipping	May 17, 2017
Conqueror	Apr 20, 2015
Constellation	Oct 2, 2016
Counter	Nov 13, 2017
Countermove Heuristic	Oct 1, 2017
Crafty	Jan 28, 2018
Cupcake	May 19, 2016
Daniel José Queraltó	Dec 31, 2017
Darmenios	Jan 7, 2016
David J. Wu	Jan 28, 2016
David Kittinger	Dec 27, 2017
DayDreamer	Aug 22, 2016
Delphil	Sep 17, 2016
Deniz Yuret	Aug 9, 2016
Diablo	May 17, 2016
DirGolem	Jun 5, 2016
Discovered Attack	Nov 8, 2010
Djinn	Feb 8, 2016
Dorky	Oct 10, 2016
Double Check	Apr 4, 2013
Dumb	Mar 10, 2018
Encoding Moves	Mar 27, 2016
Engine Testing	Feb 1, 2018
EXchess	Jan 21, 2018
Eye Movements	Jul 22, 2015
Fairy-Max	Feb 19, 2018
FCP	Jun 15, 2013
Federico Andrés Corigliano	Feb 13, 2014
Fencer	Jan 20, 2013
Ferret	Jan 7, 2016
Fixafan	Oct 2, 2015
Floyd	Sep 11, 2016
Folkert van Heusden	Nov 24, 2017
FPGA	Jul 9, 2016
Freccia	Dec 26, 2017
Freedom	Dec 28, 2017
Fridel Fainshtein	Oct 8, 2014
Galjoen	Mar 19, 2018
Gambiet	Jan 8, 2016
Garbochess	Sep 23, 2017
Genie	Feb 7, 2016
Georg von Zimmermann	May 29, 2017
George Baylor	Sep 22, 2014
Gerard Zielinski	Sep 25, 2014
Gibbon	Dec 23, 2014
Gideon	Feb 26, 2018
GiuChess	May 8, 2017
Gk	Oct 9, 2017
Glass	May 24, 2017
GNU Chess	Jan 21, 2018
Gogobello	Jul 30, 2017
Golem	May 18, 2017
GPU	Dec 16, 2017
GullChess	Jun 27, 2017
Hannibal	Oct 4, 2017
Hash Move	Oct 4, 2017
History Heuristic	Jul 19, 2017
HiTech	Mar 31, 2018
Holmes	Apr 24, 2014
Ifrit	Feb 7, 2016
Initial Position Summary	Nov 21, 2012
Interior Node Recognizer	Mar 12, 2018
Iteration	May 5, 2017
Joker IT	Sep 16, 2017
Jonathan Schaeffer	Jan 29, 2018
Kanguruh	Jan 13, 2013
Killer (NL)	Dec 15, 2017
Killer Move	Feb 16, 2017
Knowledge	Jul 22, 2017
Lachex	Jan 7, 2016
Lance Perkins	Nov 10, 2011
Lasse Hansen	Sep 1, 2015
Laurie Tunnicliffe	Jun 13, 2017
LCZero	Apr 18, 2018
Legal Move	Feb 16, 2017
Leonid Liberman	May 23, 2015
Little Wing	Oct 26, 2017
LittleThought	Nov 7, 2016
Loop (Program)	Mar 14, 2017
MadChess	Jul 4, 2017
Marc Boulé	Feb 17, 2015
Marek Strejczek	Jan 24, 2014
Mark Bromley	Oct 12, 2016
Mate-in-two	Oct 14, 2016
Mater	Apr 26, 2016
MBChess	Sep 29, 2012
Michael Gherrity	May 8, 2015
Michael Sherwin	Dec 18, 2017
MicroChess	Jul 14, 2015
Mini Chess	Jun 7, 2013
Minimax (program)	Dec 27, 2013
Move Generation	Jan 29, 2018
Move List	Jul 19, 2017
Move Ordering	Feb 27, 2018
Movei	Jan 7, 2016
Moves	Feb 19, 2018
Much	Jun 7, 2016
Murka	Nov 11, 2016
MVV-LVA	Oct 26, 2017
MyChess	Dec 25, 2017
NagaSkaki	Oct 28, 2017
Napoleon	Jun 25, 2017
Nesik	Jan 24, 2014
Niklas Fiekas	Sep 17, 2017
NoraGrace	Nov 23, 2014
Novag Micro Chess	Jan 16, 2013
NSS	Jul 14, 2015
Numpty chess	Oct 21, 2014
OliThink	May 19, 2017
One Reply Extensions	Dec 31, 2014
Origin Square	Oct 10, 2016
Ostrich	Dec 28, 2017
Othello	Jan 4, 2018
Ozalp Babaoglu	Oct 5, 2013
Patzer	Apr 5, 2017
Pedone	Jan 16, 2018
Pedro Castro	Apr 19, 2016
Perft	Sep 26, 2017
Perft Results	Feb 10, 2018
Perft(10) 20 draft 9 Positions	Nov 21, 2012
Perft(10) 400 draft 8 Positions	Nov 21, 2012
Perft(11) 20 draft 10 Positions	Nov 21, 2012
Perft(11) 400 draft 9 Positions	Nov 21, 2012
Perft(12) 20 draft 11 Positions	Nov 21, 2012
Perft(12) 400 draft 10 Positions	Nov 21, 2012
Perft(13) 20 draft 12 Positions	Nov 21, 2012
Perft(13) 400 draft 11 Positions	Nov 21, 2012
Piece-Lists	Feb 13, 2017
Pieces	Feb 19, 2018
Pieces versus Directions	Oct 6, 2016
Pigeon	Nov 2, 2016
Pin	Mar 7, 2017
Pioneer	Dec 23, 2017
Plisk	Dec 31, 2014
Praetorian	Feb 21, 2015
Promotions	Jun 6, 2017
Proscha	May 20, 2015
Protector	Oct 12, 2017
Pseudo-Legal Move	May 23, 2015
Pulse	Aug 14, 2017
Purple Haze	Oct 26, 2017
python-chess	Nov 4, 2017
Quazar	Oct 29, 2015
Querg	Dec 11, 2013
Raffaela	Apr 22, 2017
Rajah	Sep 12, 2012
Razoring	Oct 5, 2015
RDChess	May 3, 2013
Retrograde Analysis	Mar 21, 2017
ROCE	Jun 6, 2017
Rodin	Feb 7, 2016
Rotated Bitboards	Mar 7, 2017
RumbleMinze	Apr 13, 2014
Ryan Rifkin	Oct 12, 2016
Rybka	Mar 27, 2017
SAL	Dec 7, 2017
Schach (US)	Jul 21, 2016
Scidlet	May 31, 2014
SD Chess	Dec 22, 2017
Search	Feb 1, 2018
Searcher	Sep 26, 2016
SEE	Jan 14, 2013
Sensor Chess	Jun 7, 2013
Sharper	Jun 6, 2017
Shrike	Dec 30, 2012
Sidonia	May 19, 2016
Sierżant	Apr 15, 2014
Sliding Piece Attacks	May 27, 2016
Sliding Pieces	Aug 3, 2017
Sloppy	Sep 17, 2016
Small Potato	Feb 14, 2014
SnailChess	Nov 26, 2014
Snitch	Apr 7, 2016
Spartacus	Oct 17, 2016
Spector	Nov 11, 2016
Spike	Jan 7, 2016
Square Attacked By	Jan 20, 2018
Stalemate	Feb 21, 2018
Steven Edwards	Aug 26, 2017
Stuart Cracraft	May 19, 2017
Sune Fischer	Apr 7, 2014
Sunsetter	Jun 1, 2017
Super Constellation	Oct 1, 2016
Superpawn	Mar 9, 2015
Syzygy Bases	Apr 19, 2018
Table-driven Move Generation	Feb 19, 2017
Tao	Jan 8, 2016
Target Square	Oct 26, 2017
Teerapong Tovirat	Oct 21, 2014
Teki	Mar 29, 2018
Terra	Feb 11, 2015
The King	Jan 21, 2018
The switch Approach	Nov 5, 2010
Thor's Hammer	Nov 23, 2013
Thread	Apr 22, 2018
Tinker	Aug 29, 2015
Tiny Chess 86	Dec 24, 2017
UCT	Jan 22, 2018
University of Waterloo	Jan 29, 2018
Vajolet	Jan 25, 2018
Vanilla Chess	Jan 13, 2013
Vector Attacks	Dec 15, 2017
Vice	Mar 8, 2016
Warp	Nov 26, 2017
Winglet to include	Apr 25, 2015
Woodpusher	Dec 12, 2016
Workshop Chess and Mathematics	Mar 5, 2015
Yaakov HaCohen-Kerner	Aug 23, 2014
Zevra	Mar 12, 2018
Zurichess	Mar 12, 2018

Up one level

Nodes per second

GerdIsenberg — Wed, 28 Feb 2018 09:12:22 GMT

Home * Search * Node * Nodes per second

		Nodes per second (NPS) a measure of the chess program's speed. But whereas comparing different version of the same program is fine, comparisons between different engines are more difficult, since programmers use different schemes of counting nodes. The reciprocal of NPS is time per node, which translates to processor cycles per node.
RPM gauge ^[1]

Counting Nodes

Some programs include incrementing the counter after a call to:

The first approach suffers from the fact that most of selectivity techniques, where a node is pruned completely, tend to improve nodes per second. The second approach is heavily dependent on the fact whether evaluation function is called in interior nodes or in the quiescence search only. The third overemphasizes the difference between legal and pseudo-legal move generation.

Forum Posts

1995 ...

quiescent vs non-quiescent node counting by Robert Hyatt, rgcc, July 01, 1996
nodes per second - how to count? by Peter Kappler, rgcc, January 20, 1997
The Crafty-Rebel NPS challenge... by Ed Schröder, rgcc, February 26, 1997
The Crafty-Rebel NPS challenge started!!! by Ed Schröder, rgcc, March 07, 1997
Rebel-Crafty NPS Challenge by Amir Ban, rgcc, March 19, 1997
NPS challenge will end after game one... by Ed Schröder, rgcc, March 26, 1997
NPS by Andreas Mader, CCC, November 14, 1997
Node counting confusion by Don Dailey, CCC, January 17, 1998
Nodes per second........ by James Robertson, CCC, September 26, 1998
NPS and ply depth by Enrique Irazoqui, CCC, January 28, 1999
WCCC and some NPS observations by Jouni Uski, CCC, June 23, 1999 » WCCC 1999

2000 ...

DB NPS (anyone know the position used)? by Chris Carson, CCC, January 25, 2000 » Deep Blue
typical nps on single cpus by Will Singleton, CCC, February 13, 2000
What is the average nodes per second for minimax? by Leonid, CCC, June 15, 2000
Is the NPS for minimax devided by NPS in alpha-beta = 5 ? by Leonid, CCC, June 16, 2000
Is the NPS tend to grow at the end of the game? by Leonid, CCC, July 22, 2000
A story about NPS by Severi Salminen, CCC, January 26, 2001
What is the average NPS and Depth of Top Programs? by Joshua Lee, CCC, July 26, 2001
Playing the NPS game by Gian-Carlo Pascutto, CCC, September 26, 2001
High NPS vs. Low NPS by Russell Reagan, CCC, November 25, 2001
Measuring NPS... by Joel, CCC, November 17, 2002
C and C++ --- NPS by Arshad F. Syed, CCC, December 23, 2002
n/s again... by Stefano Gemma, CCC, May 07, 2004
how to calculate nps? by Peter Alloysius, CCC, July 19, 2004

2005 ...

NPS by David B. Weller, Winboard Forum, August 27, 2005 » Xpdnt
Rybka's NPS - one presumption by Vladan Vučković, CCC, February 16, 2006 » Rybka
Transposition Table and nps drop by Mathieu Pagé, CCC, February 27, 2008 » Transposition Table
To Jeroen and interested minds, re. Tiger node count by Christophe Théron, CCC, August 15, 2008
nps scaling by Daniel Shawul, CCC, March 01, 2009 » Parallel Search

2010 ...

Node counting by BB+, OpenChess Forum, January 20, 2011 » Rybka
How do you count nodes? by Edsel Apostol, CCC, September 04, 2011
Comparative nodes per second by Larry Kaufman, CCC, April 10, 2012
Current data - threads-nps efficiency up to 32 threads by Andreas Strangmüller, CCC, October 24, 2014 » Parallel Search, Thread

2015 ...

SMP NPS measurements by Peter Österlund, CCC, August 06, 2017 » Lazy SMP, Parallel Search
Nodes/sec. with last new CPU's! by Vael Jean-Paul, CCC, August 27, 2017
Reliable speed comparison: some math required by Marco Costalba, CCC, February 27, 2018 » Optimization

External Links

References

^ RPM gauge of an electric driven air compressor in the machine hall of Zollern II/IV Colliery, Dortmund Bövinghausen, Germany - part of The Industrial Heritage Trail, Image by Gerd Isenberg, September 18, 2016

What links here?

Page	Date Edited
4th Computer Olympiad	Jul 15, 2017
Adam	Feb 24, 2015
Algir	Feb 17, 2013
Andreas Mader	Dec 30, 2017
AnMon	Nov 17, 2017
Astro 64	Dec 21, 2017
Awit	Dec 22, 2017
BCP	Dec 30, 2015
Bebe	Dec 23, 2017
Belle	Jan 18, 2018
Bernie	Oct 31, 2015
Bobby	Jan 7, 2016
BP	Jan 7, 2016
Brainstorm	Jun 24, 2017
CHAOS	Dec 28, 2017
Chaturanga	Apr 4, 2013
Cheiron	Jan 7, 2016
Chepla	May 10, 2013
Chess System Tal	Jan 13, 2017
Chess-Master	Sep 7, 2017
ChipTest	Jun 19, 2016
Christophe Théron	Jan 7, 2016
Cube	Apr 23, 2017
DarkThought	Jul 3, 2018
David B. Weller	Sep 13, 2015
Deep Blue	Aug 1, 2017
Delicate Brute	Jun 7, 2016
Dictionary	Aug 24, 2017
Drago	Apr 22, 2017
E6P	Dec 17, 2016
Elektronika IM	Nov 30, 2017
Embracer	Jun 7, 2017
Eugen	Jan 7, 2016
Evaluator	Jun 5, 2013
Explorer	Dec 8, 2016
Ferret	Jan 7, 2016
Gandalf	Jan 21, 2018
Genesis NL	Dec 12, 2016
Gian-Carlo Pascutto	Jan 16, 2018
Greco	Feb 12, 2015
Grok	Aug 14, 2011
Gromit	Apr 5, 2017
HiTech	Mar 31, 2018
HpChess	Apr 2, 2015
Intellect	Jun 13, 2013
IPCCC 1991	Jun 9, 2016
Jouni Uski	Sep 28, 2017
Komodo	Mar 6, 2018
Labirint 64	Dec 21, 2017
LambChop	Nov 24, 2017
Lazy SMP	Jan 4, 2018
LChess	Jan 7, 2016
Leonid Liberman	May 23, 2015
LL Chess	May 23, 2015
Marco Costalba	Feb 28, 2018
Martin Thoresen	Apr 29, 2015
Match Statistics	Mar 31, 2018
Mathieu Pagé	Feb 14, 2018
McTobber	Jun 6, 2016
Mephisto MM V	Sep 1, 2017
Mephisto Roma	Sep 1, 2017
Mike	Jan 8, 2016
Node	Jul 20, 2015
Nodes per second	Feb 28, 2018
Nuchess	Apr 3, 2017
Optimization	Feb 28, 2018
Oracle	Sep 4, 2016
P.ConNerS	Dec 22, 2016
Parallel Search	Dec 30, 2017
Parwell	Sep 9, 2017
Pastime	Nov 3, 2015
Peter Aloysius Harjanto	Jul 21, 2015
Peter Gillgasch	May 15, 2016
Pion	May 22, 2016
Point Value by Regression Analysis	Aug 26, 2017
Prochess	Jan 7, 2016
Prodigy	Jan 19, 2018
Psion	Mar 20, 2017
Rabbit	Oct 5, 2014
Raffaela	Apr 22, 2017
Richard Lang	Jan 7, 2016
Russell Reagan	Aug 31, 2013
Rybka	Mar 27, 2017
Search Statistics	Jan 16, 2018
Severi Salminen	May 7, 2015
Shared Hash Table	Sep 11, 2017
Shess	Jan 7, 2016
Shrike	Dec 30, 2012
Shy	Jul 19, 2016
Small-C	Jan 31, 2013
Spector	Nov 11, 2016
SPOC	Jun 21, 2017
Stefano Gemma	Dec 26, 2017
Stephen B. Streater	Dec 17, 2016
Strategist	Jun 13, 2013
TDChess	Jan 10, 2013
The Sniper	Jun 3, 2016
Transposition Table	Apr 19, 2018
Turning Point	Apr 6, 2012
Vaxchess	Jan 7, 2016
Warp	Nov 26, 2017
WCCC 1980	Dec 25, 2017
WCCC 1999	Jul 13, 2017
WMCCC 1991	Sep 18, 2016
Zeus	Jan 3, 2018
Zugzwang (Program)	Dec 19, 2016

Up one Level

Occupancy

GerdIsenberg — Mon, 19 Sep 2016 08:10:04 GMT

Home * Chess * Squares * Occupancy

		The Occupancy refers to the boolean property of a square. It is occupied if any piece exclusively resides on that square, otherwise the square is empty. In bitboards, the occupancy or occupied bitboard refers the set of all squares occupied by any piece. Thus, it is the union of all piece bitboards, which is used for instance in calculating sliding piece attacks. Likely, while the piece bitboards are updated incrementally, the occupancy is updated incrementally as well, rather than calculated from up to 12 piece bitboards each time. Alternatively, if needed more often, the complement set of the occupancy, the set of all empty squares is exclusively kept inside the board-definition and a cheap not-instruction is done to calculate the occupancy on the fly. Other programs keep disjoint white and black pieces, to "or" them if the occupancy is actually needed. The appearance of multiple, redundant occupied bitboards, which are flipped, mirrored or rotated are eponym of bitboard methods related to sliding piece attack generation, most notably rotated and reverse bitboards.
Occupied ^[1]

Forum Posts

Occupancy Variations by CDaley11, OpenChess Forum, January 25, 2013 » Magic Bitboards

External Links

References

^ Besetzt! (Occupied) - Toilet exhibition at Umspannwerk Recklinghausen, today RWE Technology museum in Recklinghausen, Germany, and part of The Industrial Heritage Trail of the Ruhr area - Portable toilet labeled Rock:Klo with Frank Zappa Toilet Poster inside, Photo by Gerd Isenberg, September 16, 2016

What links here?

Page	Date Edited
Array	Dec 1, 2016
Bitboard Board-Definition	Jun 23, 2014
Bitfoot	Sep 8, 2015
Blockers and Beyond	Mar 21, 2014
BMI1	Mar 24, 2014
Board Representation	Dec 11, 2017
Captures	Oct 1, 2017
Center Control	Jan 17, 2018
Classical Approach	Jan 28, 2018
Fill Algorithms	Nov 6, 2013
First Rank Attacks	Aug 28, 2010
Gk	Oct 9, 2017
Golch	Dec 7, 2017
Hash Table	Jan 1, 2018
Hashing Dictionaries	Mar 1, 2014
Hyperbola Quintessence	Mar 25, 2017
Initial Position	Apr 14, 2018
Kindergarten Bitboards	Aug 1, 2017
Lachex	Jan 7, 2016
Magic Bitboards	Apr 13, 2018
Obstruction Difference	May 27, 2016
Occupancy	Sep 19, 2016
Occupancy of any Line	Sep 16, 2016
OliThink	May 19, 2017
On an empty Board	Mar 18, 2014
Othello	Jan 4, 2018
Pattern Recognition	Sep 8, 2017
Pawn Push	Mar 27, 2010
Pieces	Feb 19, 2018
Pseudo-Legal Move	May 23, 2015
Reverse Bitboards	Aug 29, 2015
Rotated Bitboards	Mar 7, 2017
Ryan Mack	Jan 18, 2011
SBAMG	Dec 4, 2016
Shifted Bitboards	Jan 9, 2011
Sliding Piece Attacks	May 27, 2016
Sliding Pieces	Aug 3, 2017
Square Attacked By	Jan 20, 2018
Square Control	Sep 15, 2016
Squares	Feb 15, 2015
SSSE3	Aug 8, 2017
Subtracting a Rook from a Blocking Piece	Dec 2, 2016
Traversing Subsets of a Set	Oct 14, 2016
Vajolet	Jan 25, 2018
Winglet	Apr 26, 2015

Up one Level

Occupancy of any Line

GerdIsenberg — Fri, 16 Sep 2016 20:25:28 GMT

Home * Board Representation * Bitboards * Sliding Piece Attacks * Occupancy of any Line

		Occupancy of any Line, unlike rank attacks, the problem arises for files and diagonals how to get scattered occupancies to consecutive bits of a dense lookup index. In the past, prior to early 2000, 64-bit multiplication was unfeasible - much too slow.
Line Occupancy ^[1]

Avoiding Multiplication

Avoiding Multiplication

Rotated Bitboards

One solution was the invention of rotated bitboards - to keep and maintain three additional rotated occupied bitboards, with consecutive bits for the appropriate rays. Similar to the bit-layout mentioned in rotate by 90 degrees and pseudo rotate by 90 degrees.

Collapsed Files

Other techniques were about to hash the masked line with parallel prefix shifts to collapse ranks, diagonals or anti-diagonals along the files ^[2] ^[3]:

int collapsedFilesIndex(U64 b) {
   b |= b >> 32;
   b |= b >> 16;
   b |= b >>  8;
   return b & 0xFF;
}

In 32-bit mode, assembly programmers may collapse files to register AL in five instructions, saving >> 32 and >> 8:

or  eax, edx
mov edx, eax
shr eax, 16
or  eax, edx
or  al, ah

Collapsed Ranks

For a line along files (as well as diagonals or anti-diagonals), a little more trickery is needed:

int collapsedRanksIndex(U64 b) {
   b |= b >>  4;
   b |= b >>  2;
   b |= b >>  1;
   b &= C64(0x0101010101010101):
   b |= b >>  7;
   b |= b >> 14;
   b |= b >> 28;
   return b & 0xFF;
}

If it is exclusively about to collapse files to ranks, one can save the first three parallel prefix shifts, but shift right by file-index:

int collapsedRanksIndex(U64 b, enumFile file) {
   b  = b >> file;
   b &= C64(0x0101010101010101):
   b |= b >>  7;
   b |= b >> 14;
   b |= b >> 28;
   return b & 0xFF;
}

Using Multiplication

Recent 64-bit processors, such as core 2 or K8 have a amazingly fast 64-bit multiplication, so that flip- or rotation-tricks as mentioned in diagonals to rank or flip about the diagonal are competitive nowadays.

Collapsed Files

int collapsedFilesIndex(U64 b) {
   const U64 aFile   = C64(0x0101010101010101);
   return (b * aFile) >> 56;
}

or in 32-bit mode:

int collapsedFilesIndex(U64 b) {
   unsigned int folded = (unsigned int)b | (unsigned int)(b >> 32);
   return (folded * 0x01010101) >> 24;
}

Collapsed Ranks

int collapsedRanksIndex(U64 b) {
   const U64 aFile   = C64(0x0101010101010101);
   const U64 antiDia = C64(0x0102040810204080);
 
   b |= b >> 4;   // No masking needed
   b |= b >> 2;   //    "         "
   b |= b >> 1;   //    "         "
   return ((b & aFile) * antiDia) >> 56;
}

or dedicated for files

int collapsedRanksIndex(U64 b, enumFile file) {
   const U64 aFile   = C64(0x0101010101010101);
   const U64 antiDia = C64(0x0102040810204080);
 
   b  = b >> file;
   return ((b & aFile) * antiDia) >> 56;
}

Those techniques are actually used in kindergarten bitboards, considering the inner six bits for a denser lookup.

Forum Posts

Re: Rotated bitboards by Urban Koistinen, rgcc, October 31, 1997
Re: Some thoughts on Dann Corbit's rotated alternative by Steffan Westcott, CCC, March 03, 2006
Kindergarten bitboards without multiplying by Piotr Cichy, CCC, August 07, 2009 » Kindergarten Bitboards

External Links

Bit Gather Via Multiplication by Vlad Petric, Dr. Petric's Technical Blog, September 17, 2013 ^[4]

References

^ Besetzt! (Occupied) - Toilet exhibition at Umspannwerk Recklinghausen, today RWE Technology museum in Recklinghausen, Germany, and part of The Industrial Heritage Trail of the Ruhr area - Row of occupied portable toilets, Photo by Gerd Isenberg, September 16, 2016
^ Re: Rotated bitboards by Urban Koistinen, rgcc, October 31, 1997
^ Re: Some thoughts on Dann Corbit's rotated alternative by Steffan Westcott, CCC, March 03, 2006
^ Demystifying the Magic Multiplier?

What links here?

Page	Date Edited
Amundsen	Sep 3, 2013
Cassandre	Jul 5, 2013
Chezzz	Jan 20, 2013
Flipping Mirroring and Rotating	Oct 14, 2016
General Setwise Operations	Feb 25, 2018
Gk	Oct 9, 2017
Kindergarten Bitboards	Aug 1, 2017
Kurt	Apr 20, 2014
Occupancy	Sep 19, 2016
Occupancy of any Line	Sep 16, 2016
OliThink	May 19, 2017
Parallel Prefix Algorithms	Jun 22, 2016
Pepito	Nov 27, 2014
Population Count	Sep 3, 2017
Prophet	Sep 30, 2017
Rotated Bitboards	Mar 7, 2017
Sayuri	Oct 1, 2017
Sliding Piece Attacks	May 27, 2016
Smash	May 11, 2016
Steffan Westcott	Jan 21, 2014
Urban Koistinen	Apr 20, 2014

Up one Level

Piece Recognition

GerdIsenberg — Fri, 08 Sep 2017 19:04:21 GMT

Home * Chess * Position * Piece Recognition

		Piece Recognition, (Chess Board or Chess Position Recognition) the ability of dedicated chess computers or chess playing robots to automatically recognize all the pieces on a chessboard, or in computer vision to convert an image of a real chessboard with pieces, or a chess diagram into a machine readable format specifying a chess position, such as Forsyth-Edwards Notation (FEN) or Extended Position Description (EPD).
Chessgame ^[1]

Computer Vision

Piece Recognition Boards

Computer Vision

Piece recognition is an interesting topic in computer vision, machine learning and pattern recognition using one or more cameras along with digital image processing and object recognition, more recently supported by deep learning techniques as demonstrated by Daylen Yang with his Chess ID project ^[2].

Piece Recognition Boards

The user interface task to enter moves on a sensory board is often implemented with pressure sensitive or magnetic switches to determine origin and target squares with the implicit knowledge of the game state which piece was on the origin square and moved. The incremental update during game play starting from the initial position requires some care to keep internal and external board representation in sync, specially if analyzing with taking moves back. Here, real piece recognition offers not only much more comfort in entering arbitrary positions, but also more fault tolerant move recognition for dedicated units.

Piece recognition sensory boards require special electronics, and pieces with integrated passive components, such as piece type and piece color specific coils on ferrite core of a LC circuit. Selected via file- and rank multiplexer, the LC circuit forms a inductive coupled feedback loop of an amplifier forcing oscillation in piece type specific resonance, which could be measured or filtered, to detect the piece (if any) on the selected square. As reported by Robert Hyatt, Ken Thompson already had a piece recognition board based on coils in the base of the pieces, as demonstrated at ACM 1978 with Belle ^[3]. Along with Henry S. Baird, Ken Thompson further contributed to computer vision applied to reading chess a few years later ^[4].

Selected Systems

Publications

2000 ...

Timothée Cour, Rémy Lauranson, Matthieu Vachette (2002). Autonomous Chess-playing Robot. École Polytechnique, pdf, pdf
David Urting, Yolande Berbers (2003). MarineBlue: A Low-Cost Chess Robot. Katholieke Universiteit Leuven, RA 2003. pdf

2010 ...

Arturo De la Escalera, Jose María Armingol (2010). Automatic Chessboard Detection for Intrinsic and Extrinsic Camera Parameter Calibration. Sensors, vol. 10, No. 3
Cynthia Matuszek, Brian Mayton, Roberto Aimi, Marc Peter Deisenroth, Liefeng Bo, Robert Chu, Mike Kung, Louis LeGrand, Joshua R. Smith, Dieter Fox (2011). Gambit: A Robust Chess-Playing Robotic System. Proc. of ICRA 2011, pdf ^[5] ^[6] ^[7]
Nandan Banerjee, Debal Saha, Atikant Singh, Gautam Sanyal (2011). A Simple Autonomous Robotic Manipulator for Playing Chess Against any Opponent in Real Time. pdf
Cheryl Danner, Mai Kafafy (2015). Visual Piece Recognition. Stanford University, pdf ^[8]
Raghuveer Kanchibail, Supreeth Suryaprakash, Suhas Jagadish (2016). Chess Board Recognition. School of Informatics and Computing, Indiana University, pdf

Forum Posts

Re: Tasc R30 v 2.5? by Steven Schwartz, CCC, September 08, 1999
Re: What happened to TASC? by Steven Schwartz, CCC, October 27, 2001
Web-cam based chessboard position digital recognition? by Clifton Prince, Chess.com forum, June 04, 2016

External Links

References

^ Schachspiel by Lür Henning Flake, from the Technophilia art exhibition at Henrichshütte Ironworks - Museum of iron and steel, Hattingen, North Rhine-Westphalia, Germany, part of The Industrial Heritage Trail of the Ruhr area, Photo by Gerd Isenberg, October 01, 2016
^ Building Chess ID – Medium by Daylen Yang
^ Re: Tasc R30 v 2.5? by Robert Hyatt, CCC, September 08, 1999
^ Henry S. Baird, Ken Thompson (1990). Reading Chess. IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 12, No. 6, pdf
^ The Gambit Manipulator at UW RSE-lab
^ Personal Robotics at Intel Labs Seattle
^ Chess Playing Robot
^ Visual Chess Recognition - Semantic Scholar
^ Cheryl Danner, Mai Kafafy (2015). Visual Piece Recognition. Stanford University, pdf

What links here?

Page	Date Edited
Chess Champion Mark V	Sep 7, 2017
Chess Position	Sep 10, 2017
Chess-Master	Sep 7, 2017
Dedicated Chess Computers	Feb 20, 2018
DGT Board	Feb 21, 2018
Entering Moves	Sep 7, 2017
Mephisto Module Systems	Sep 7, 2017
Millennium ChessGenius	Mar 1, 2018
Pattern Recognition	Sep 8, 2017
Piece Recognition	Sep 8, 2017
Pieces	Feb 19, 2018
Raspberry Turk	Sep 7, 2017
Revelation II	Jan 8, 2018
Robots	Feb 20, 2018
Sensory Board	Mar 1, 2018
Tasc	Sep 7, 2017
Tasc R30	Sep 7, 2017
Tasc R40	Sep 7, 2017
TASC SmartBoard	Feb 25, 2018
User Interface	Feb 21, 2018

Up one level

Playing Strength

GerdIsenberg — Sat, 31 Mar 2018 07:29:37 GMT

Home * Chess * Playing Strength

		Playing Strength, (Performance, Skill Level) of a chess player, or chess playing entity, program or engine, reflects the ability to win against other players, given by a number or other element of an ordered set such as an Elo number. The ability to solve test-positions, that is, finding the specified, likely one and only best move, might be an indicator for various particular engine skills, but does not necessarily correlate with playing strength. In his Parallelism and Selectivity in Game Tree Search lecture, Tord Romstad introduced the Worst Moves Observation (WMO), which states the practical playing strength is not primarily determined by the quality of the players best moves nor average moves, but by the quality of the players worst moves.
Dragon and Snake on ambos ^[1]

Measuring

A statistical valid method to measure playing strength within a defined confidence interval is to play an appropriate huge number of games with both sides versus a wide range of different opponents ^[2] with symmetric time constraints, and to apply match statistics. Performance isn't measured absolutely; it is inferred from wins, losses, and draws against other players or engines. Players' rating depend on the ratings of their opponents, and the results scored against them ^[3]. While relative playing strength of chess engines is not strictly transmissive over various time controls, the number of games played is more relevant than their duration, the todays de facto standard in measuring playing strength is parallel playing fast chess with (ultra) short time control, such as blitz, bullet or even lightning chess, as for instance used in the Fishtest framework of Stockfish ^[4].

Strength

The strength of a chess program depends on many things, the quality and efficiency of the algorithms involved to determine the best move of a position, the balance of the so called search versus knowledge tradeoff to evaluate or compare leaf nodes of a search tree, how to shape that tree and to propagate a score up to the root, and time management, that is how to allocate time for searching a move under time control requirements. Time used is roughly proportional to the number of visited nodes of the common depth-first search inside an iterative deepening frame, which grows exponentially by its effective branching factor raised to the power of search depth. Playing strength might be improved over the (playing) time due to learning algorithms.

Publications

1970 ...

F. Donald Bloss (1973). Rate your own Chess. Van Nostrand Reinhold Inc.
Tony Marsland, Paul Rushton (1973). Mechanisms for Comparing Chess Programs. ACM Annual Conference, pdf
Peter W. Frey (ed.) (1977). Chess Skill in Man and Machine. Springer, New York, N.Y. 2nd ed. 1983
James Gillogly (1978). Performance Analysis of the Technology Chess Program. Ph.D. Thesis. Tech. Report CMU-CS-78-189, Carnegie Mellon University, CMU-CS-77 pdf » Tech
Arpad Elo (1978). The Rating of Chessplayers, Past and Present. Arco Publications ^[5]
Don Beal (1978). Handicapping Computer Chess Programs. ICCA Newsletter, Vol. 1, No. 2
David Cahlander (1979). Strength of a Chess Playing Computer. ICCA Newsletter, Vol. 2, No. 1
Jack Good (1979). On the Grading of Chess Players. Personal Computing, Vol. 3, No. 3, pp. 47
Gary L. Ratliff (1979). Practical Rating Program. Personal Computing, Vol. 3, No. 9, pp. 62 » Bloss
Frieder Schwenkel (1979). Berating the ratings system. Personal Computing, Vol. 3, No. 11, pp. 77 » Ratliff, Bloss
John Shaposka (1979). "JS" Takes the Bloss Test. Personal Computing, Vol. 3, No. 12, pp. 75 » Ratliff, Bloss
Editor (1979). Chess Ratings from Problem Solving. Personal Computing, Vol. 3, No. 12, pp. 77 » CAPS II, Chess Problems, Compositions and Studies

1980 ...

Floyd R. Kirk (1980). Bloss Flunks Test. Personal Computing, Vol. 4, No. 8, pp. 72 » Ratliff, Bloss
David E. Welsh (1980). Rating Boris 2.5. Personal Computing, Vol. 4, No. 10, pp. 78 » Boris 2.5
W. W. Foster (1980). Six Test Problems for Chess Playing Machines. Personal Computing, Vol. 4, No. 10, pp. 81
David E. Welsh (1980). Rating Boris 2.5 - Part II. Personal Computing, Vol. 4, No. 11, pp. 87
Ken Thompson (1982). Computer Chess Strength. Advances in Computer Chess 3
Ivan Bratko, Danny Kopec (1982). A Test for Comparison of Human and Computer Performance in Chess. Advances in Computer Chess 3
Danny Kopec, Ivan Bratko (1982). The Bratko-Kopec experiment: a comparison of human and computer performance in chess. Advances in Computer Chess 3
Danny Kopec, Enrique Irazoqui, Ivan Bratko (1983). The Updated Bratko-Kopec Test. Computer Chess Digest Annual pp. 45-63
Alexander Szabo (1984). Computer-Chess Tactics and Strategy. M.Sc. Thesis, University of British Columbia, pdf
Göran Grottling (1984). The Truth about their Strength. ICCA Journal, Vol. 7, No. 4
Göran Grottling (1985). How to Bracket the Truth in Playing Strength. ICCA Journal, Vol. 8, No. 1
Monroe Newborn (1985). A Hypothesis Concerning the Strength of Chess Programs. ICCA Journal, Vol. 8, No. 4
Peter W. Frey (1986). Algorithmic Strategies for Improving the Performance of Game-Playing Programs. In Doyne Farmer, Alan Lapedes, Norman Packard, Burton Wendroff (Ed.) (1986). Evolution, Games and Learning: Models for Adaptation in Machines and Nature. Proceedings of the Fifth Annual International Conference of the Center, Elsevier
Hans Berliner, Gordon Goetsch, Murray Campbell, Carl Ebeling (1989). Measuring the Performance Potential of Chess Programs. Advances in Computer Chess 5
Eric Hallsworth (1989). Playing Levels. Computer Chess News Sheet 23, pp 2, pdf hosted by Mike Watters

1990 ...

Hans Berliner, Gordon Goetsch, Murray Campbell, Carl Ebeling (1990). Measuring the Performance Potential of Chess Programs. Artificial Intelligence, Vol. 43, No. 1
Eric Hallsworth (1990). Speed, Processors and Ratings. Computer Chess News Sheet 25, pp 6, pdf hosted by Mike Watters
Hans Berliner, Danny Kopec, Ed Northam (1991). A taxonomy of concepts for evaluating chess strength: examples from two difficult categories. Advances in Computer Chess 6, pdf
Steve Maughan (1992). Are You Sure It's Better? Selective Search 40, pp. 21, pdf hosted by Mike Watters
Warren D. Smith (1993). Rating Systems for Gameplayers, and Learning. ps
Luis Antunes, Luis Moniz, Carlos Azevedo (1993). Rb+: the Dynamic Estimation of the Opponent's Strength. INESC-ID, Lisbon, Portugal » RB
Robert Hyatt, Monroe Newborn (1997). CRAFTY Goes Deep. ICCA Journal, Vol. 20, No. 2 » Crafty

2000 ...

Ernst A. Heinz (2000). New Self-Play Results in Computer Chess. CG 2000
Ernst A. Heinz (2001). Self-play Experiments in Computer Chess Revisited. Advances in Computer Games 9
Ernst A. Heinz (2001). Modeling the “Go Deep” Behaviour of CRAFTY and DARK THOUGHT. Advances in Computer Games 9 » Crafty, Dark Thought
Ernst A. Heinz (2001). Self-Play, Deep Search and Diminishing Returns. ICGA Journal, Vol. 24, No. 2
Guy Haworth (2002). Self-play: Statistical Significance. 7th Computer Olympiad Workshop
Guy Haworth (2002). Reference Fallible Endgame Play. 7th Computer Olympiad Workshop, pdf
Guy Haworth (2003). Self-Play: Statistical Significance. ICGA Journal, Vol. 26, No. 2
Ernst A. Heinz (2003). Follow-Up on Self-Play, Deep Search, and Diminishing Returns. ICGA Journal, Vol. 26, No. 2

2005 ...

Jan Renze Steenhuisen (2005). New Results in Deep-Search Behaviour. ICGA Journal, Vol. 28, No. 4, pdf
Matej Guid, Ivan Bratko (2006). Computer Analysis of World Chess Champions. ICGA Journal, Vol. 29, No. 2, pdf ^[6]^[7]
Matej Guid, Ivan Bratko (2006). Computer Analysis of Chess Champions. CG 2006
Matej Guid, Ivan Bratko (2007). Factors affecting diminishing returns for searching deeper. CGW 2007 » Crafty, Rybka, Shredder, Diminishing Returns
Shogo Takeuchi, Tomoyuki Kaneko, Kazunori Yamaguchi, Satoru Kawai (2007). Visualization and Adjustment of Evaluation Functions Based on Evaluation Values and Win Probability. AAAI 2007, pdf
Matej Guid, Ivan Bratko (2007). Factors affecting diminishing returns for searching deeper. ICGA Journal, Vol. 30, No. 2, pdf
Matej Guid, Aritz Pérez, Ivan Bratko (2007). How trustworthy is Crafty's analysis of world chess champions? CGW 2007 » Crafty
Matej Guid, Aritz Pérez, Ivan Bratko (2008). How trustworthy is Crafty's analysis of world chess champions? ICGA Journal, Vol. 31, No. 3, pdf
Rémi Coulom (2008). Whole-History Rating: A Bayesian Rating System for Players of Time-Varying Strength. CG 2008
Giuseppe Di Fatta, Guy McCrossan Haworth, Kenneth Wingate Regan (2009). Skill Rating by Bayesian Inference. CIDM 2009, pdf ^[8]
Guy McCrossan Haworth, Kenneth Wingate Regan, Giuseppe Di Fatta (2009). Performance and Prediction: Bayesian Modelling of Fallible Choice in Chess. Advances in Computer Games 12, pdf

2010 ...

Diogo R. Ferreira (2010). Predicting the Outcome of Chess Games based on Historical Data. IST - Technical University of Lisbon ^[9]
Matej Guid (2010). Search and Knowledge for Human and Machine Problem Solving. Ph.D. thesis, University of Ljubljana
Kenneth W. Regan, Guy Haworth (2011). Intrinsic Chess Ratings. AAAI 2011, pdf, slides as pdf ^[10]
Kenneth Wingate Regan, Bartłomiej Macieja, Guy McCrossan Haworth (2011). Understanding Distributions of Chess Performances. Advances in Computer Games 13, pdf
Trevor Fenner, Mark Levene, George Loizou (2011). A Discrete Evolutionary Model for Chess Players' Ratings. Physics and Society, arXiv:1103.1530v2
Matej Guid, Ivan Bratko (2011). Using Heuristic-Search Based Engines for Estimating Human Skill at Chess. ICGA Journal, Vol. 34, No. 2
Rémi Coulom (2012). Paired Comparisons with Ties: Modeling Game Outcomes in Chess. pdf preprint ^[11]
Diogo R. Ferreira (2012). Determining the Strength of Chess Players based on actual Play. ICGA Journal, Vol. 35, No. 1
Diogo R. Ferreira (2013). The Impact of the Search Depth on Chess Playing Strength. ICGA Journal, Vol. 36, No. 2
Erik Varend (2014). Quality of play in chess and methods for measuring. pdf ^[12] ^[13]

2015 ...

Shogo Takeuchi, Tomoyuki Kaneko (2015). Estimating Ratings of Computer Players by the Evaluation Scores and Principal Variations in Shogi. ACIT-CSI
Guy Haworth, Tamal T. Biswas, Kenneth W. Regan (2015). A Comparative Review of Skill Assessment: Performance, Prediction and Profiling. Advances in Computer Games 14
Chu-Hsuan Hsueh, I-Chen Wu, Wen-Jie Tseng, Shi-Jim Yen, Jr-Chang Chen (2015). Strength Improvement and Analysis for an MCTS-Based Chinese Dark Chess Program. Advances in Computer Games 14
Jean-Marc Alliot (2017). Who is the Master? ICGA Journal, Vol. 39, No. 1, draft as pdf » Stockfish, Who is the Master?

Forum Posts

1990 ...

Weakest Chess Program needed by Jones Maxime Murphy, rgc, November 12, 1991
Estimating Playing Strength of Computers (was: Re: Rating of Radio Shack 1650) by Peter Marko, rgc, September 15, 1992 » SciSys Explorer
Rating boundaries by Kevin Stokker, rgc, January 14, 1993
Cognitive Psychology and Chess Skill by John Rummel, rgc, June 07, 1994 » Cognition

1995 ...

Primitive Chess Program by David Ewart, rgc, June 09, 1995
Rating of perfect chess by an18...@anon.penet.fi, rgc, July 17, 1995
Theoretical chess rating question... by Cyber Linguist, rgcc, April 17, 1996
Statistical validity of medium-length match results by Bruce Moreland, rgcc, February 15, 1997
ELO performance? by Stefan Meyer-Kahlen, CCC, May 22, 1999 » Match Statistics, Pawn Advantage, Win Percentage, and Elo
from "Scacco": No steps forward in Computer Chess in the Last years !? by Gianluigi Masciulli, CCC, September 18, 1999

2000 ...

Strength of the engine in chess programs by Rolf Tueschen, CCC, May 20, 2002
Value of playing different versions of a program against each other by Tom King, CCC, January 06, 2003 » Engine Testing
Rules of thumb for strength estimation? by Albert Bertilsson, CCC, April 25, 2003

2005 ...

bayeselo: new Elo-rating tool, applied to CCT7 by Rémi Coulom, CCC, February 13, 2005 » CCT7
a beat b,b beat c,c beat a question by Uri Blass, CCC, May 16, 2007
A thought about ratings by Dave Dyer, Computer Go Archive, December 10, 2007 » Go
Re: A thought about ratings by Don Dailey, Computer Go Archive, December 10, 2007
Re: A thought about ratings by Edward de Grijs, Computer Go Archive, December 10, 2007
Re: A thought about ratings by Don Dailey, Computer Go Archive, December 10, 2007

2008

Glaurung Mac OS X: New GUI, now with adjustable strength. by Tord Romstad, CCC, May 18, 2008 » Glaurung
Artificial stupidity - making a program play badly by Tord Romstad, CCC, May 20, 2008
New testing thread by Robert Hyatt, CCC, August 07, 2008 » Engine Testing
Hardware vs Software by Charles Roberson, CCC, December 02, 2008

2009

Speed/ELO relationship, and question to engine programmers by Russell Reagan, CCC, March 02, 2009
Elo Calcuation by Edmund Moshammer, CCC, April 19, 2009
different kinds of testing by Don Dailey, CCC, November 09, 2009

2010 ...

How to reduce playing strenght to play against humans by Fermin Serrano, CCC, March 05, 2010
Current skill command (Crafty) results by Robert Hyatt, CCC, July 21, 2010 » Crafty
harware vs software advances by Don Dailey, CCC, September 08, 2010
hardware advances - a different perspective by Robert Hyatt, CCC, September 09, 2010
old crafty vs new crafty on new hardware by Robert Hyatt, CCC, September 11, 2010
Crafty tests show that Software has advanced more by Don Dailey, CCC, September 12, 2010
Final results - Crafty - hardware vs software by Robert Hyatt, CCC, September 13, 2010
Deep Blue vs Rybka by Don Dailey, CCC, September 13, 2010 » Deep Blue, Rybka

2011

Ply vs ELO by Andriy Dzyben, CCC, June 28, 2011
Increase in Elo ..Question For The Experts by Steve B, CCC, December 05, 2011

2012

StockFish LS with LimitStrength feature by Alexander Schmidt, CCC, January 01, 2012 » Stockfish
Depth vs playing strength by David Whitten, CCC, January 09, 2012
Reducing Strength by Ted Wong, CCC, March 15, 2012
Human Elo ratings: averages and standard deviations by Jesús Muñoz, CCC, March 18, 2012
Elo versus speed by Peter Österlund, CCC, April 02, 2012
Rybka odds matches and the strength of engines by Kai Laskos, CCC, June 09, 2012 » Rybka
Elo points gain from doubling time by Kai Laskos, CCC, December 10, 2012
A word for casual testers by Don Dailey, CCC, December 25, 2012

2013

Noise in ELO estimators: a quantitative approach by Marco Costalba, CCC, January 06, 2013
Scaling at 2x nodes (or doubling time control) by Kai Laskos, CCC, July 23, 2013 » Doubling TC, Diminishing Returns, Playing Strength, Houdini
How much elo is pondering worth by Michel Van den Bergh, CCC, August 07, 2013 » Pondering
Contempt and the ELO model by Michel Van den Bergh, CCC, September 05, 2013 » Contempt Factor
ELO rating and thinking time by Henk van den Belt, CCC, November 22, 2013

2014

Playing strength development - increasing time control by Andreas Strangmüller, CCC, April 17, 2014
How many Elo points change for a doubling of uP time? by Jay Rodrequez, CCC, August 14, 2014
Using the Stockfish position evaluation score to predict victory probability by unavoidablegrain, Tumblr, September 28, 2014 » Pawn Advantage, Win Percentage, and Elo, Stockfish
Elo estimation using quasi-Monte Carlo integration by Branko Radovanovic, CCC, September 30, 2014
Questions regarding rating systems of humans and engines by Erik Varend, CCC, December 06, 2014

2015 ...

How to dumb down/weaken/humanize an engine algorithmically? by Dominik Klein, CCC, January 18, 2015
computing elo of multiple chess engines by Alexandru Mosoi, CCC, August 09, 2015
Name for elo without draws by Marcel van Kervinck, CCC, September 02, 2015
The future of chess and elo ratings by Larry Kaufman, CCC, September 20, 2015
ELO error margin by Fabio Gobbato, CCC, October 17, 2015
testing multiple versions & elo calculation by Folkert van Heusden, CCC, October 27, 2015

2016

a direct comparison of FIDE and CCRL rating systems by Erik Varend, CCC, February 22, 2016 » FIDE, CCRL
Computer Chess Strength by John Fishburn, CCC, February 28, 2016
How much benefit from opening book? by John Fishburn, CCC, March 06, 2016 » Opening Book
Computer chess progress over say the last 20 years? by Martin Fierz, CCC, March 10, 2016
Computer chess progress over the last 20 years! by Martin Fierz, CCC, March 13, 2016
Computer Chess Progress: Stockfish 7 vs Ruffian 1.0.5 by Martin Fierz, CCC, March 17, 2016 » Stockfish, Ruffian
skill levels by Alexandru Mosoi, CCC, April 28, 2016
Strategies for weaker play levels by Evert Glebbeek, CCC, June 28, 2016
ELO inflation ha ha ha by Henk van den Belt, CCC, September 16, 2016 » Delphil, Stockfish, Match Statistics, TCEC Season 9 ^[14]
About expected scores and draw ratios by Jesús Muñoz, CCC, September 17, 2016
Perfect play by Patrik Karlsson, CCC, September 28, 2016
Doubling of time control by Andreas Strangmüller, CCC, October 21, 2016 » Doubling TC, Diminishing Returns, Playing Strength, Komodo
Stockfish 8 - Double time control vs. 2 threads by Andreas Strangmüller, CCC, November 15, 2016 » Doubling TC, Diminishing Returns, Playing Strength, Stockfish
L3 cache, RAM and other performance factors by Nimzy, Rybka Forum, December 04, 2016 » Memory
Absolute ELO scale by Nicu Ionita, CCC, December 17, 2016
Diminishing returns and hyperthreading by Kai Laskos, CCC, December 27, 2016 » Diminishing Returns, Match Statistics, Thread

2017

Progress in 30 years by four intervals of 7-8 years by Kai Laskos, CCC, January 19, 2017 » Match Statistics
Crafty Play By Elo ( Crafty v25.3) by Michael B, CCC, January 23, 2017 » Crafty
6-men Syzygy from HDD and USB 3.0 by Kai Laskos, CCC, April 04, 2017 » Komodo, Syzygy Bases, USB 3.0
Scaling of engines from FGRL rating list by Kai Laskos, CCC, April 07, 2017 » FGRL
Low impact of opening phase in engine play? by Kai Laskos, CCC, April 18, 2017 » Opening
How to simulate a game outcome given Elo difference? by Nicu Ionita, CCC, April 25, 2017
Wilo rating properties from FGRL rating lists by Kai Laskos, CCC, May 01, 2017 » FGRL
RAM speed and engine strength by John Hartmann, CCC, May 03, 2017 » RAM
Symmetric multiprocessing (SMP) scaling - SF8 and K10.4 by Andreas Strangmüller, CCC, May 05, 2017 » Lazy SMP, Komodo, Stockfish
Symmetric multiprocessing (SMP) scaling - K10.4 Contempt=0 by Andreas Strangmüller, CCC, May 11, 2017 » SMP, Komodo, Contempt Factor
Symmetric multiprocessing (SMP) scaling - SF8 Contempt=10 by Andreas Strangmüller, CCC, May 13, 2017 » SMP, Stockfish, Contempt Factor
Another attempt at comparing Evals ELO-wise by Kai Laskos, CCC, May 22, 2017 » Evaluation
Testing endgame strength by Álvaro Begué, CCC, June 21, 2017 » Endgame, Engine Testing, RuyDos
Invariance with time control of rating schemes by Kai Laskos, CCC, July 22, 2017 ^[15]
Ways to avoid "Draw Death" in Computer Chess by Kai Laskos, CCC, July 25, 2017
ELO measurements by Peter Österlund, CCC, August 06, 2017 » Lazy SMP, Parallel Search
an interesting study from Erik Varend by scandien, Hiarcs Forum, August 13, 2017 ^[16]
Wall and Regression by Srdja Matovic, CCC, August 31, 2017 ^[17] ^[18]
Scaling from FGRL results with top 3 engines by Kai Laskos, CCC, September 26, 2017 » FGRL, Houdini, Komodo, Stockfish
"Intrinsic Chess Ratings" by Regan, Haworth -- seq by Kai Middleton, CCC, November 19, 2017
Re: "Intrinsic Chess Ratings" by Regan, Haworth -- by Kenneth Regan, CCC, November 20, 2017 » Who is the Master?
ELO progression measured by year by Ed Schroder, CCC, December 13, 2017

2018

Is modern chess software lossless or lossy? by Meni Rosenfeld, CCC, January 10, 2018 » Selectivity
Feed bayeselo with pure game results without PGN by Sergei S. Markoff, CCC, March 08, 2018
Elo measurement of contempt in SF in self-play by Michel Van den Bergh, CCC, March 10, 2018 » Contempt, Stockfish
Time control envelope in top engines could be improved? by Kai Laskos, CCC, March 13, 2018 » Time Management
LCZero: Progress and Scaling. Relation to CCRL Elo by Kai Laskos, CCC, March 28, 2018 » LCZero
Elostat Question by Michael Sherwin, CCC, March 30, 2018

External Links

Chess Player

Chess Engines

Analysis

Computers choose: who was the strongest player?, ChessBase News, October 30, 2006
Computer analysis of world champions by Søren Riis, ChessBase News, November 02, 2006 ^[19]
Chessanalysis homepage by Erik Varend ^[20]

Rating Systems

Chess rating system from Wikipedia
Chessmetrics from Wikipedia
Elo rating system from Wikipedia
Elo Win Probability Calculator by François Labelle
Arpad Elo and the Elo Rating System by Dan Ross, ChessBase News, December 16, 2007
Kirr's Chess Engine Comparison KCEC - Draw rate » KCEC
Who is the Master? by Jean-Marc Alliot » Who is the Master?
How Should Chess Players Be Rated? by Martin Koppe, CNRS News, April 25, 2017
Ranking chess players according to the quality of their moves by Frederic Friedel, ChessBase News, April 27, 2017
Rating List Stats by Ed Schroder » CCRL, Match Statistics

Misc

References

^ Photo by Gerd Isenberg, September 18, 2016, detail of the Flottmann gate, Art Nouveau theme of Dragon and Sun designed by Carl Weinhold, art director of blacksmith and foundry Füssmann und Fleeth, Essen, exposed at the industrial and trade exhibition 1902 in Düsseldorf, and baught by Heinrich Flottmann as gate for his jackhammer factory, today adjacent to the exhibition and event space Flottmann-Hallen in Herne, North Rhine-Westphalia, Germany, and part of The Industrial Heritage Trail of the Ruhr area, "The dragon is a symbol of physical strength and intelligence with respect to the snake that symbolizes the tough, glowing wrought iron" from Flottmann-Tor – Hün un Perdün, see also Image by Gerd Biedermann, and Flottmann-Hallen - Historie (German)
^ A word for casual testers by Don Dailey, CCC, December 25, 2012
^ Elo rating system - Mathematical details - Wikipedia
^ Stockfish Testing Framework
^ Elo's Book: The Rating of Chess Players by Sam Sloan
^ Computers choose: who was the strongest player?, ChessBase News, October 30, 2006
^ Computer analysis of world champions by Søren Riis, ChessBase News, November 02, 2006
^ Bayesian inference from Wikipedia
^ How I did it: Diogo Ferreira on 4th place in Elo chess ratings competition | no free hunch
^ "Intrinsic Chess Ratings" by Regan, Haworth -- seq by Kai Middleton, CCC, November 19, 2017
^ Re: EloStat, Bayeselo and Ordo by Rémi Coulom, CCC, June 25, 2012
^ Questions regarding rating systems of humans and engines by Erik Varend, CCC, December 06, 2014
^ chess statistics scientific article by Nuno Sousa, CCC, July 06, 2016
^ Delphil 3.3b2 (2334) - Stockfish 030916 (3228), TCEC Season 9 - Rapid, Round 11, September 16, 2016
^ Normalized Elo (pdf) by Michel Van den Bergh
^ Chessanalysis homepage by Erik Varend
^ wall - Wiktionary
^ regression - Wiktionary
^ Matej Guid, Ivan Bratko (2006). Computer Analysis of World Chess Champions. ICGA Journal, Vol. 29, No. 2, pdf
^ an interesting study from Erik Varend by scandien, Hiarcs Forum, August 13, 2017

What links here?

Page	Date Edited
Albert Bertilsson	Jun 6, 2017
Andreas Strangmüller	May 15, 2017
Automated Tuning	Feb 27, 2018
Awit	Dec 22, 2017
CHAOS	Dec 28, 2017
Chess	Jan 21, 2018
Chess Problems, Compositions and Studies	Feb 19, 2018
Chessmaster	Jan 21, 2018
Cognition	Dec 8, 2017
Contempt Factor	Mar 10, 2018
Crafty	Jan 28, 2018
Delphil	Sep 17, 2016
Depth	Feb 25, 2018
Diogo R. Ferreira	Sep 4, 2016
Drago	Apr 22, 2017
Draw	Apr 14, 2018
Ed Northam	Sep 4, 2016
Edward de Grijs	Dec 30, 2016
Engine releases	Apr 23, 2018
Engine Testing	Feb 1, 2018
Evaluation	Feb 1, 2018
Evaluation Discontinuity	Oct 9, 2017
FGRL	Oct 1, 2017
Fire	Oct 12, 2017
Fortress	Feb 1, 2018
Glaurung	Mar 14, 2017
Go	Jan 24, 2018
Hiarcs	Feb 25, 2018
Houdini	Apr 14, 2018
John Philip Fishburn	May 3, 2017
Jos Uiterwijk	Aug 11, 2017
Kai Laskos	Jan 21, 2018
Kaissa	Apr 9, 2018
Knowledge	Jul 22, 2017
Komodo	Mar 6, 2018
Lazy SMP	Jan 4, 2018
LCZero	Apr 18, 2018
MadChess	Jul 4, 2017
Match Statistics	Mar 31, 2018
Mate Distance Pruning	Jun 2, 2017
Meep	Sep 4, 2016
Memory	Dec 8, 2017
Michel Van den Bergh	Mar 10, 2018
Nicu Ionita	May 3, 2017
Nodes per second	Feb 28, 2018
Opening	Jun 25, 2017
Opening Book	Feb 26, 2018
Oracle	Sep 4, 2016
Parallel Search	Dec 30, 2017
Pawn Advantage, Win Percentage, and Elo	Dec 20, 2017
Playing Strength	Mar 31, 2018
Rodent	Jan 11, 2018
Search	Feb 1, 2018
Search with Random Leaf Values	Apr 23, 2018
Selectivity	Jan 12, 2018
SPSA	May 8, 2017
Stefan Meyer-Kahlen	Jun 19, 2017
Stockfish	Apr 7, 2018
Stockfish's tuning method	May 21, 2017
Syzygy Bases	Apr 19, 2018
TCEC Season 9	Nov 6, 2017
Texel's Tuning Method	Dec 2, 2017
Thread	Apr 22, 2018
Time Management	Mar 20, 2018
Uri Blass	Feb 26, 2018

Up one Level

PolyGlot

GerdIsenberg — Wed, 17 Jan 2018 09:45:13 GMT

Home * Software * Utilities * PolyGlot
Home * Knowledge * Opening Book * PolyGlot

		PolyGlot, an adapter ^[1] that allows UCI engines to use interfaces and GUIs supporting the Chess Engine Communication Protocol, developed by Fabien Letouzey and modified by Fonzy Bluemers ^[2]. Polyglot is open source, licensed under the GPL, and is able to run on various operating systems, which allows to run UCI engines not only under Windows with its native chess GUIs, but also under Linux and Mac OS using XBoard. PolyGlot 1.4 provides a simplistic opening book implementation ^[3], referred as bin-opening book format. As far as XBoard/WinBoard is concerned since 2018, Polyglot is scheduled for retirement. The latest beta package of WinBoard did not contain any Polyglot, but relied on UCI2WB instead, which is variant agnostic, and supports all UCI dialects (USI, UCCI, UCI-Cyclone, Arena960). Polyglot is useless for anything other than ordinary Chess ^[4].
Hildegard Skowasch - Untitled ^[5]

Forum Posts

2004

UCI2WB "replacement" project news by Fabien Letouzey, Winboard Forum, March 23, 2004
Wanted: tester for new UCI adapter (UCI w/ WinBoard) by Fabien Letouzey, Winboard Forum, March 26, 2004
PolyGlot by Salvo Spitaleri, Winboard Forum, April 01, 2004
Experimental PolyGlot by Fabien Letouzey, Winboard Forum, April 06, 2004
minor change in PolyGlot by Fabien Letouzey, Winboard Forum, April 08, 2004
PolyGlot and pondering by Fabien Letouzey, Winboard Forum, April 13, 2004 » Pondering
What is Polyglot in computer chess?? by Jouni Uski, CCC, April 14, 2004
New PolyGlot by Fabien Letouzey, Winboard Forum, April 15, 2004
Polyglot queries... by Roger Brown, Winboard Forum, April 18, 2004
PolyGlot news by Fabien Letouzey, Winboard Forum, April 19, 2004
New PolyGlot by Fabien Letouzey, Winboard Forum, April 21, 2004
New PolyGlot by Fabien Letouzey, Winboard Forum, April 27, 2004
PolyGlot 1.0 by Fabien Letouzey, Winboard Forum, April 30, 2004
New: PolyGlot 1.0 (UCI adapter) by Fabien Letouzey, CCC, May 04, 2004
To Roger o Volker, about Polyglot by Carlos Pesce, Winboard Forum, May 10, 2004
PolyGlot glitch by Fabien Letouzey, Winboard Forum, June 08 2004
Safe I/O by Fabien Letouzey, Winboard Forum, December 10, 2004

2005 ...

PolyGlot 1.2 (multi-platform UCI adapter) available by Fabien Letouzey, CCC, January 30, 2005
Polyglot & log-file by Stefan Knappe, Winboard Forum, February 10, 2005
PolyGlot 1.3 available (UCI adapter) by Fabien Letouzey, CCC, June 04, 2005
A bug in Polyglot 1.3 ? by Niyaz Khasanov, Winboard Forum, July 01, 2005
Input thread under polyglot by Peter Fendrich, Winboard Forum, August 15, 2005
How to make book using polyglot? by Russell, CCC, October 19, 2005
Unanswered polyglot questions by Thomas Logan, CCC, October 20, 2005
Problem with PolyGlot 1.3 by Álvaro Begué, CCC, October 30, 2005

2006

Books for polyglot by Carlos Pesce, Winboard Forum, January 01, 2006
Threading issue under Polyglot by Nathan Thom, Winboard Forum, September 18, 2006 » Thread

2007

Question for Polyglot book experts by Günther Simon, Winboard Forum, January 02, 2007
Polyglot books use with any UCI engine under CB GUI ! by Marc Lacrosse, CCC, October 28, 2007

2008

Polyglot 1.4w5 by Fonzy Bluemers, Winboard Forum, September 09, 2008
Polyglot glitch? (feature?) by Günther Simon, Winboard Forum, November 14, 2008
Polyglot now supports the UCI protocol:-) by Michel Van den Bergh, CCC, December 22, 2008 » UCI

2009

Polyglot 1.4w22 by Fonzy Bluemers, Winboard Forum, May 25, 2009

2010 ...

Polyglot : a small request by Olivier Deville, Winboard Forum, October 01, 2010
Problem using XBoard + Polyglot + Zippy on FICS by Ben-Hur Carlos Langoni, CCC, November 15, 2010 » XBoard, Free Internet Chess Server
New Polyglot and opening books by Olivier Deville, Winboard Forum, December 29, 2010
polyglot compile instructions by matematiko, Winboard Forum, April 16, 2011
polyglot en passant square by Marco Belli, CCC, September 12, 2013 » En passant
CTG to polyglot format by matematiko, Winboard Forum, October 23, 2013 » CTG
Polyglot 2.0.3 memory limit by Juan Molina, CCC, December 12, 2014

2015 ...

stockfish uci commands in polyglot by mike schoonover, CCC, February 16, 2015
Winboard 4.8.0b and PolyGlot 2.0.3 adjudication issues by Ferdinand Mosca, CCC, February 22, 2015
Polyglot-format books: large boards by Harm Geert Muller, CCC, March 04, 2015

2016

Polyglot and make-book by Ed Schröder, CCC, February 26, 2016
all the old tools are vanishing... by Jack Crawford, CCC, February 27, 2016
REBEL | ProDeo book available in Polyglot format by Ed Schröder, CCC, March 05, 2016 » Rebel, Pro Deo
Polyglot 1.4 Update by Michael B, CCC, March 13, 2016
icsdroneng and polyglot by Alexandru Mosoi, CCC, March 11, 2016
opening book standards by Jef Kaan, CCC, August 10, 2016
Opening book in bin-format by Alexander Schmidt, CCC, August 17, 2016
Polyglot book learning by Günther Simon, CCC, August 24, 2016 » Book Learning
Where can I find the current PolyGlot version? by Frank Quisinsky, CCC, September 10, 2016
book .bin by diego suarez, CCC, September 11, 2016
Polyglot dump-book problem/bug/limit by Günther Simon, CCC, September 26, 2016
Polyglot pickBest by Dennis Sceviour, CCC, December 29, 2016 » WinBoard

2017

How to Make a .BIN opening book (for non programmers?) by Brendan J. Norman, CCC, April 03, 2017
How do you use .bin books? by John Wentworth, CCC, June 21, 2017
Viewing a bin book file by Giovanni Lavorgna, CCC, July 30, 2017
Cannot download Polyglot or KingSlayer source code by Dean Menezes, CCC, December 31, 2017
Re: Cannot download Polyglot or KingSlayer source code by Harm Geert Muller, CCC, January 01, 2018 » UCI2WB

External Links

Chess adapter

hgm.nubati.net Git - polyglot.git hosted by Harm Geert Muller
GitHub - sshivaji/polyglot: Polyglot chess opening book program hosted by Shivkumar Shivaji
Polyglot 1.4w by Fonzy Bluemers
Polyglot book format by Michel Van den Bergh
Polyglot opening book reading by Niklas Fiekas » python-chess
PolyGlot - Hispanic Chess Engines
Create a Polyglot Chess Opening Book by Steve Maughan, YouTube Video » Maverick, SCID, David J. Barnes, Ed Schröder

Misc

polyglot - Wiktionary
Polyglot (disambiguation) from Wikipedia
Polyglotism from Wikipedia
Polyglot (book) from Wikipedia
Polyglot (computing) from Wikipedia
Temur Kvitelashvili - 21 guitars (1990), YouTube Video

References

^ Adapter pattern from Wikipedia
^ Information and rules to participate from WBEC Ridderkerk (Internet Archive)
^ Polyglot book format by Michel Van den Bergh
^ Re: Cannot download Polyglot or KingSlayer source code by Harm Geert Muller, CCC, January 01, 2018
^ Hildegard Skowasch - Untitled (2015), Flottmann 30 hoch - 30 years anniversary exhibition, Flottmann-Hallen in Herne, North Rhine-Westphalia, Germany, part of The Industrial Heritage Trail of the Ruhr area, Photo by Gerd Isenberg, September 18, 2016

What links here?

Page	Date Edited
ABK	Feb 1, 2017
Ben-Hur Carlos Vieira Langoni Junior	Dec 17, 2013
Book Learning	Jan 1, 2017
Brendan J. Norman	Jan 11, 2018
Carballo	Oct 2, 2016
Chess Engine Communication Protocol	Mar 4, 2018
Chiron	Sep 24, 2017
Cinnamon	Sep 23, 2017
Claudia	Jun 1, 2016
CTG	Aug 22, 2016
DayDreamer	Aug 22, 2016
Dennis Sceviour	Feb 14, 2018
Dictionary	Aug 24, 2017
Donna	Aug 17, 2017
En passant	Jan 16, 2018
Fabien Letouzey	Feb 5, 2018
Fonzy Bluemers	Sep 5, 2013
Galjoen	Mar 19, 2018
InBetween	Jan 21, 2018
JikChess	Nov 29, 2015
KnockOut	Sep 20, 2016
LittleThought	Nov 7, 2016
Logging	Jan 20, 2018
Marco Belli	Jan 6, 2018
Marvin	Feb 10, 2018
Maverick	Jan 7, 2016
Michel Van den Bergh	Mar 10, 2018
Nathan Thom	Mar 15, 2013
Niyaz Khasanov	Mar 22, 2014
Olivier Deville	Sep 29, 2016
Opening Book	Feb 26, 2018
PolyGlot	Jan 17, 2018
Pro Deo	Apr 5, 2017
python-chess	Nov 4, 2017
Rebel	Feb 25, 2018
Shivkumar Shivaji	Oct 24, 2017
Sidonia	May 19, 2016
Texel	Oct 9, 2017
Thread	Apr 22, 2018
UCI	Mar 4, 2018
UCI2WB	Jan 21, 2018
Utilities	Jan 20, 2018
Vice	Mar 8, 2016
Wb2UCI	Feb 1, 2018
WCCC 2017	Dec 31, 2017
WinBoard	Mar 4, 2018
XBoard	Jan 21, 2018
Zeta Dva	Apr 11, 2017

Up one Level

Raptor LU

GerdIsenberg — Wed, 05 Oct 2016 19:06:27 GMT

Home * Engines * Raptor LU

		Raptor, a private chess engine by Steve Webber. Raptor had its tournament debut in 2013, when it participated at the CCT15 ^[1], and played the CCT16 and a strong WCRCC 2015 gaining a fourth place and 6/9, where its parallel search used 8 threads under Windows 8 ^[2]. Raptor further participated at the ICGA WCCC 2016 and WCSC 2016 at Leiden University, operated and represented by book author Wolfgang Zugrav, with a strong 4th place at the uniform platform tournament ahead of Hiarcs, Ginkgo and The Baron. A few weeks later, Raptor was quite successful in rapid chess at the WCRCC 2016, 7th place with 8½/15.
Iron Raptor ^[3]

Namesake

Raptor by Frédéric Louguet

Forum Posts

Re: Thanks for a Great CCT This Year! by Steve Webber, CCC, February 25, 2013 » CCT15
Re: CEGT 40/4 update online by Steve Webber, CCC, March 09, 2013

External Links

Chess Engine

415 Raptor 20150614 x64 1CPU - 2717 at CEGT 4/40

Misc

References

^ Re: Thanks for a Great CCT This Year! by Steve Webber, CCC, February 25, 2013 » CCT15
^ The 2015 Ninth Annual World Computer Rapid Chess Championships - Participants
^ Iron Raptor at headframe of shaft 7, former coal mine Erin, Castrop-Rauxel, North Rhine-Westphalia, Germany, part of The Industrial Heritage Trail of the Ruhr area, Photo by Gerd Isenberg, September 18, 2016, see also Category:Zeche Erin Schacht 7 from Wikimedia Commons, in paticular image by Frank Vincentz, September 20, 2012

What links here?

Page	Date Edited
CCT15	Oct 21, 2014
CCT16	May 13, 2014
Engines	Mar 10, 2018
Raptor	Jul 20, 2015
Raptor LU	Oct 5, 2016
TCEC Season 9	Nov 6, 2017
WCCC 2016	Sep 18, 2017
WCRCC 2015	Jul 19, 2015
WCRCC 2016	Jun 27, 2017
WCRCC 2017	Jun 27, 2017
WCSC 2016	Sep 18, 2017
Wolfgang Zugrav	Jul 13, 2016

Up one Level

Rays

GerdIsenberg — Thu, 20 Oct 2016 19:31:06 GMT

Home * Chess * Rays

		A Ray is part of a line from a starting square in one particular direction. Lines are either the orthogonal ranks and files or the diagonal lines, diagonals and anti-diagonals. The length of a ray varies from zero until seven squares.
The Enlightenment ^[1]

Ray Directions

Following Compass rose gives the directions and single step increments of an 8x8 Board:

  northwest    north   northeast
  noWe         nort         noEa
          +7    +8    +9
              \  |  /
  west    -1 <-  0 -> +1    east
              /  |  \
          -9    -8    -7
  soWe         sout         soEa
  southwest    south   southeast

Forum Posts

Extract direction (ray) informations from two squares by Mathieu Pagé, CCC, June 18, 2013 » Direction, Square Attacked By
Table-less bitboards (bitrays?) by Harm Geert Muller, CCC, June 18, 2013 » Board Representation

External Links

Ray from Wikipedia
Stingray from Wikipedia
Michael Brecker Band - Original Rays, Wiesen, Austria, July 9, 1989, YouTube Video
Michael Brecker, Mike Stern, Joey Calderazzo, Jeff Andrews, Adam Nussbaum

References

^ Photo by Gerd Isenberg, September 18, 2016, detail of the Flottmann gate, Art Nouveau theme of Dragon and Sun designed by Carl Weinhold, art director of blacksmith and foundry Füssmann und Fleeth, Essen, exposed at the industrial and trade exhibition 1902 in Düsseldorf, and baught by Heinrich Flottmann as gate for his jackhammer factory, today adjacent to the exhibition and event space Flottmann-Hallen in Herne, North Rhine-Westphalia, Germany, and part of The Industrial Heritage Trail of the Ruhr area, "In the upper center of the gate is a symbol of The Enlightenment, a female head with a ray ring." from Flottmann-Tor – Hün un Perdün, see also Image from the archive of the city of Herne, and Flottmann-Hallen - Historie (German)

What links here?

Page	Date Edited
AlphaZero	Feb 10, 2018
Belle	Jan 18, 2018
Bitfoot	Sep 8, 2015
Blockers and Beyond	Mar 21, 2014
Check	Feb 1, 2018
Chess	Jan 21, 2018
Classical Approach	Jan 28, 2018
Direction	Oct 6, 2016
Discovered Attack	Nov 8, 2010
Discovered Check	Feb 1, 2018
Hyperbola Quintessence	Mar 25, 2017
Mathieu Pagé	Feb 14, 2018
On an empty Board	Mar 18, 2014
Pin	Mar 7, 2017
Rays	Oct 20, 2016
Reverse Bitboards	Aug 29, 2015
Ryan Mack	Jan 18, 2011
Shifted Bitboards	Jan 9, 2011
Skewer	Oct 22, 2014
Sliding Piece Attacks	May 27, 2016
Sliding Pieces	Aug 3, 2017
Square Attacked By	Jan 20, 2018
Squares	Feb 15, 2015
Table-driven Move Generation	Feb 19, 2017
Vector Attacks	Dec 15, 2017

Up one Level

Wikispaces : chessprogramming - items matching description

Aspiration Windows

Table of Contents

Gradual Widening

PVS and Aspiration

See also

Publications

Forum Posts

1995 ...

2000 ...

2005 ...

2010 ...

2015 ...

External Links

References

What links here?

Asymmetric evaluation

Table of Contents

See also

Publications

Forum Posts

1997 ...

2000 ...

2010 ...

References

What links here?

Auto232

Table of Contents

Windows

See also

Publications

Forum Posts

1997 ...

2000 ...

2005 ...

2010 ...

External Links

References

What links here?

Candidates (Bitboards)

Table of Contents

Candidate and Faker

Advanced Candidates

Less Advanced

The Sneaker

See also

External Links

References

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Coiled

Table of Contents

Features

Board Representation

Search

Evaluation

Misc

See also

Forum Posts

External Links

Chess Engine

Misc

References

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Elephant

Table of Contents

Description

See also

Forum Posts

External Links

Chess Engine

Chess and Variants

Misc

References

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Fritz

Table of Contents

Etymology

Selected Games

Null Move

Descriptions